Even if you don't feel it slows down with time, various things happen... For example, my power went out for just a fraction of a second, long enough to reboot my machine, a few months back. After that, my printer would spit out gibberish whenever I tried to print anything. I googled around for it, and it's a common problem, however the various fixes didn't work for me. ATI's drivers have improved, but it used to be a good idea to reinstall any time you changed them, and updates are generally at most a few months apart. There are plenty of other good reasons. Simply put, M$ doesn't have to polish the product for lack of competition, and so little stuff like the printer bug proliferates, and it catches up to you sooner or later, usually sooner... I get the idea that people who don't see it as a problem don't use their computer as much as those who do see it as a problem. My pc was on 24/7 for years, and I use it a lot. I'm bound to have a different experience than someone who turns it on twice a week to check their email.