Just a fyi on this...
Having installed windows 10 on over 150 machines of various types and manufacturers including customs.... desktops and laptops/netbooks and so forth.... both clean and upgrade installs...
1: There is an insane number of different configured systems, programs, not to mention a plethora of administrative privileged programs such as AV/AM software that plays havoc with the upgrade process and has a tendency to make a royal mess of things in unpredictable ways.
2: Almost any system i've upgraded that experienced weird issues... including net connection issues, were usually due to user configuration changes implemented previously or software that was making active modifications to how things were accessed, again av/am software frequently was related to the issues. Alternatively there are numerous people that "didn't experience problem on their previous windows install".... but do now.... you'd be surprised how often an upgrade or fresh install of either windows will show issues... and the question is "well it wasn't a problem before!". Hardrives frequently fail, but not completely, bad sectors mount up, and with so many with laptops, they have a very high failure rate in a slow process that generally doesn't show itself until either way down the road, OR if an upgrade to windows is done that ends up trying to either overwrite an insignificant bad sector with critical data, resulting in corruption. BSODs usually result down the road, but not necessarily. Another factor is a faulty and intermittent Memory module that only rears it head when you do something major like a windows upgrade/install.
3: It's ALWAYS best to backup your files, as well as program settings and do a COMPLETE full wipe of the drive and then a fresh install of windows, in this case windows 10. If you haven't upgrades, you can still do a fresh install via running the windows 10 within your current windows, allowing it to generate the activation validiation certificate (xml file) in which you simply copy it to a usb.... and then wipe and install windows 10, after installation, dump the xml file back in the necessary location, reboot, and it should validate and activate fully once connected to the internet. Refer to the link below on how you could copy the necessary the data file and do this... http://www.ghacks.net/2015/08/30/how-to-clean-install-windows-10-directly-without-upgrade/
Now as far as windows 10 is concerned for supported hardware.... the basics are simply this:
Windows 10 is vastly more efficient and friendly/faster/resource managed and overall supported across numerous components that date very far back when DIRECTLY compared to windows xp sp3 with update, windows vista sp2 with updates, windows 7 sp1 with updates and windows 8.x. Now the 32bit version will run back a lot further than the 64bit version due to the specific rules set in place for 64bit. Execute bit for example MUST be supported entirely on 64bit version, so there are people with some of the early 64bit cpus that cannot upgrade to 10 let alone upgrade to windows 8.1, some people can't even install windows 8.0 64bit, and there are some good/bad reasons as to why which is in the end irrelevant.
I've systems from 2000 and even earlier that work rather incredibly well on windows 10.. though in terms of being useable today on the internet and for general tasks, it is best to make certain you have the following as BARE minimums if you plan on doing anything at all really, even simple, if you want something useable.
1: CPU ~> Make certain this is a dual core.. if not a dual core.. make sure it's a single core with hyper threading. I've had some fairly decent results with machine running a Pentium 4 with HT for example... though this goes WAY Back... but for the sake of sanity and ease of use without getting mad and chucking things about, while windows 10 runs quite a bit better than all the previous versions on these machines... by todays standards using it, it's about as low end as you want to bother with unless you are indeed used to using a snail stuck in molasses.
2: The oldest systems are restricted to basically 1536MB of ram ... windows 10 will opperate easily within this to a point.... again absalutely bare minimum, but i would not recommend bothering. It would be best to make sure you have at LEAST 2GB of ram.... 4GB recommended, and if you have more, well, you're laughing then. I've several machines i had built for my customers in 2005/2006 that are fully capable of running with 4GB of ram, and i've moved those machines to windows 10 already without a hitch, and impressively, they are outperforming many of the newer cheap machines available today, quite amazing for 10 year old computers considering, then again i did have a standard back then that ensured they'd be more than compatible for a long time. All those machines used AMD's x2 series cpus which by todays standards aren't that great, but they are more than sufficient for everyday tasks and even the occasional game.. in fact they still can play many of the modern games with 4gb of ram and a modernish graphics card.
3: Outside of cpu and ram, there isn't much holding back anyone from using windows 10, even obsolete video graphics cards are well supported within windows 10 to a point, in fact windows 10 provides newer and more efficient drivers for legacy hardware than all the version of windows xp/vista/7/8.x, i was pleasantly surprised to find old intergrated intel graphics drivers that allow me to play 720p content on such an old chip and even manage 60fps video playback on youtube without completely killing the system. One of these systems is an old netbook that happens to have the first interation of an intel atom cpu that is a "sort of dual core" solution, if it were single core, i'm sure it'd be extremely poor performing. Driver packages for intel/amd/nvidia used in windows vista or newer work very well in windows 10, Very old legacy hardware, example being AMD's original 9500xt from way back when, use a very very old set of drivers, that install fine on windows 10 surprisingly.
You can download a full copy of windows 10 or windows 10 pro in either 32bit or 64bit for free directly from microsoft... burn your own DVD installation disk OR make a bootable USB (if you happen to have a modern system capable of reading bootable usbs).https://www.microsoft.com/en-ca/software-download/windows10
If you have windows 7 pro or ultimate, windows 8.x pro, make sure to download the pro version of windows 10 to perform a clean and/or upgrade install. If you have just windows 7 home premium/home basic/starter, windows 8.x non-pro, then get the strictly non pro version of windows 10. As far as 32bit or 64bit, IF your system supports 64bit, it is BEST to move to that asap, only use 32bit if you simply have no choice.
Lastly, windows 10 is not restricted to UEFI systems... legacy is fully supported obviously considering the age of the systems i've dealt with. Additionally the way the activation system works, is that it creates a unique identification for basically your motherboard in the system and then activates, every clean install afterwards can be performed without needing the "upgrade" file or doing an upgrade from a previous version of windows, you simply just skip the parts where it asks for a cd key and once you're in windows and connected to the net, it verifies what it sees for the idenfication is checks it with the activation database from the previous. IF you happen to replace your motherboard, you simply will have to call/reactivate and usually it'll work straight away. Alternatively if you move your copy of windows 7/8.x to a new system, MAKE certain to remove windows 10 from the old system prior to installing windows 7/8.x on the new machine in order for you to process a new upgrade identification for windows 10... windows 10 won't activate unless windows 7/8.x has been activated on the new system, you may still have to call into microsoft on getting windows 10 to upgrade activate, after which you'll be able to do clean installs on that new machine endlessly. This however is not guaranteed for a new machine.
Lastly, make certain that once you have windows 10 installed... ALLOW it to process all updates PRIOR to attempting to install anything, Microsoft has started to heavily use cumulative updates, and plan on release yearly builds (perhaps sooner or further apart). They also plan on no longer releasing "new versions of windows" nearly as often as all the updates will be rolled into one and provided for free to windows 10 users. This is good news IMO.
Once windows 10 is fully updated, make certain to download the latest chipset/video/audio drivers for your hardware, windows 10 is VERY good at detecting wireless/ethernet components and installing necessary drivers for that, but if you happen to run into a problem with net connections, try downloading the latest drivers for them as well, just make sure it's not AM/AV software interfering, you'd be surprised how often this happens.