You might be able to use AMD's overdrive tool. It looks pretty nice I've never tried it as I went Intel recently but now that I'm looking at it I might try it on my parents HP pc with an Athlon X2. Here is some info about it.
Here is where to download it.
Overclocking from within windows isn't usually recommended regardless of how you are doing it though. If you have any extra money you might want to pick up a new mobo. There are some really great ones for ocing the black edition cpus even in the 50-70 dollar price range. Let me know if that software works for you though it's worth a try.