I still use the same OS I've been installing for years, along with some newer versions of course. What I have to do is keep up with all the newest "fixes" to keep Microsoft's WGA campaign happy. Of course, none of the fixes last forever. It's a constant battle between MS and those who work so diligently to defeat it! I simply glean from the effort!
The fix I've provided here deletes KB905474 which looks to see if your OS is legit and the warning bubble that replaces your desktop background if you fail the KB905474 test.
The easiest way I have found to test a "fixed" OS is to go Microsoft's site and try to download something useful to you that requires a "Genuine Check." If I can get it, I'm OK. If I can't, it just gives a warning without altering anything on my OS and I know I've got more work to do!