I'm not sure how much SC2 and WoW take up as I don't play those, but add those two up, and then take a look down the list in Add/Remove programs. How many are more than 100 or 200 Mb? add those up, even just approximately.
How much music do you have? even if you don't know the size, how many songs? Windows XP, Vista, or 7? XP takes up relatively little, but on my system 7 takes up 20 Gb by itself. You'll probably find that once you add all the seemingly small things that you have a pretty big number.
If you can, go to your (in XP) My Computer -> Local Disk C: and right click on Documents and Settings, go to Properties, or (in Vista/7) go to Computer ->Local Disk C: and right click on Users. Take a look at the Size value in the window that pops up. That'll tell you if the culprit lies primarily in the size of the installed programs or in your Music/Videos/Documents/Downloads.
If neither of these areas seem to add up to anywheres near the 232 Gigs of your drive, then it might be time to suspect a virus. I DO NOT recommend Norton. Personally, I run avast Free and that seems to do the trick, but so far I've avoided any major viruses