This site is basically Windows 7 specific. A number of the tips, tricks and procedures here will work on other versions, but the only one they've been tested on is Win7.
The reason this is Win7-only should be obvious. WinXP is ancient history at this point, Vista never was very popular, and unless you have a tablet computer, there's really no reason for Win 8 or 10, simply because they didn't add much in the way of features, and all they really did was make the general Desktop environment harder to work with. So, t'heck with 'em.
Standard Disclaimer: As on any site like this, I completely don't guarantee a single thing here will work, and if your tower suddenly turns into a molten fireball of melted plastic and twisted metal from trying one of my suggestions, well, sorry about that.
The most important page on the site is the Setup page. If you do or read nothing else, at least skim through that page. You really need to learn how to turn off the unnecessary background routines that new programs install. When it comes to the general operation of your system, that's as important as everything else combined.