Re: pc problems AGAIN :(
Allow me to set this straight.
PCs generally run slow because of spyware, adware, malware in general that load up when your computer starts. That is they come in throngs, and stay there. If you had a ton of viruses, most likely you'd have a ton of application crashes, and windows rebooting/being totally unstable/unusable. That, or fragmentation, but there's only so much you can do about that.
Your grail for anti-spyware is, of course, Spybot S&D. Update it, scan it, it should remove a lot of your problems. Don't use ANYTHING else, the other software is just ghastly. Spybot is continually updated, the immunization blocks suspect websites from entering your computer (i.e. in the hosts file), and after you update it, clean it, and immunize it, pretty much nothing should ever enter your computer and slow it down. Not even on the naughty websites. No offense, I meant myself. :P
As far as the antivirus goes, your best bet (and the one I use, after years of trying various cruddy software) is avast! antivirus. It's the best, it has a ton of shields and protections, pretty decent scan speed, and! the best part -- it has both a FREE and a paid version. It's actually so good I bought it (and I am loathe to buy software in general!). Always runs in the background, it DOESN'T gobble up memory like Vista does (I'm running the 64bit Vista, and it likes to chew on 1,5 of my 4 gigs of RAM), and it does what it's required to do.
Don't be so quick to ALWAYS reinstall windows every time a problem pops up. I've lost some things that way. If you use avast & spybot, you shouldn't ever have problems.
There's several ways you could go about fixing your registry, although it's not really a critical step. Have a go at TuneUp Utilities, they have a pretty decent registry cleaner, and I believe you can use it for 30 days fully unlocked. That's a pretty decent deal, it should tide you over. It also has a relatively decent partition defragmenter (which you should run if you're out on an errand or something; takes around 16 hours on a 700gig partition full to the brim, but it works better as a result. Of course, less capacity on a partition, the less it takes).
Also, it's a good idea to run Disk Cleanup (yeah, the thing in windows) as it usually clears up the muck Windows likes to accumulate like the pig it is. (and it's usually a fair deal). Don't bother with the defragmenter in Windows, it's junk.
Way I go about bussiness and cleaning up is going to control panel, uninstalling whatever programs I don't *really* use, or perhaps deleting old ones that the computer still thinks it has, and then clean the registry values with TuneUp Utilities.
Also, you may want to switch to K-Lite codec pack for viewing movies, and whatnot. I've found other codec packs tend to make a mess of the individual codecs, and the computers gets confused. And slow. And annoying.
If you have any questions, feel free to ask. This is the kinda stuff I excel at. No offense, guys, I've just spent a fair amount of time breaking my computer, and I'm tired of reinstalling windows. (he said, being ashamed at how all the people talk about guitars and he knows very little)