I have just finished installing Windows 10 on this dusty old computer! The feeling is... indescribable, like seeing a really lame dude driving a super fast sports car.
(I have promised myself to upgrade this computer "someday", but never got around to it.)
Windows 10 comes as a free update if you are running on Windows 7, 8, or 8.1 at the moment. If you're not sure how, or you've seen Windows notify you about the upgrade moons ago but it has yet to start, fret not! - You can force the upgrade onto your system, here's how:
IMPORTANT! (With a serious face)
Make sure you've done the update for ALL of the optional components in your Windows Update, i.e: Microsoft Silverlight, Desktop Skype, Security blah blah blah... and all those shenanigans.
Failure to do so will cause your Windows 10 update to end up unable to proceed halfway, or during installation.
Once everything is done;
1. Go to C:/Windows/SoftwareDistribution/Download
2. Delete everything in the folder, like an old habit
3. Open up command prompt as an Admin (right-click command prompt and select "Run as Admin")
4. Run, Forrest, run!
5. Type/Copy-paste this command ->
wuauclt.exe /updatenow
6. Hit ENTER, and the update should start immediately (check in the control panel, Windows Update)
Enjoy!