One of my classmates recently told me about CCleaner. It's the first pc tool that I've come across that is free and fixes the registry problems that it detects. I've checked out a few others in the past that were "free" tools, but most of them just cleaned up a couple things and then said, "you have all these problems, but you need to pay us for more."
As you might know by now, your computer builds up a lot of extra files. It Microsoft sends updates, but doesn't bother to automatically remove the old garbage when it updates... so your computer just keeps getting filled up with junk. Useless registry files clutter things up, and eventually the computer is just slow.
So, since my computer was running slow today while browsing a few of my regular sites, and clearing the cache and temporary internet files in my browser didn't seem to make a difference, I decided to run CCleaner and see what it could do. At this point, I'm impressed. My browser speed was boosted immensely and other applications are opening much faster too!
If you want to try it yourself go to
http://www.ccleaner.com/. They offer a few other free tools there too.