I don't think you should bother with re-installing your OS at all, unless of course, if what you want is to clear out your HDD. I use this free to use software 'Glary utilities', it fixes up your registry problems and clears some temporary files which slows your pc down a little. By the way I read its review before downloading on cnet.com and it was trusted and a good software according to the review. Also there are a few temporary files (couple of mb's) which can slow your overall performance down that don't get removed even with glary utilities (but I do both because it's just better). The way to do that is to go into start, in the search bar type %temp%. This opens your temporary files folder and I delete everything in there (a few files aren't removable from that too so you can't do anything about those). And finally clean your recycling bin often. I've been doing all these steps for quite a while and on my 2 and a half year old 600$ (usd) laptop, I can play games fairly decently along with listening to music and surfing the net. GL