I've seen this in the forums before but can't find the answer...
I have Virtual PC 7.0.2 running under OS X 10.4.8 on a 12" iBook G4. Over time, the Virtual PC file grows quite large--right now it's 5 GB, but will grow with use to 7 or 8 GB, even if I don't install any more apps. There was a utility listed here at one point that would zero out the unused disk space on a WinXP volume and subsequently make the virtual disk much smaller, and I even had it installed at one point and it worked quite well--then my WinXP file got corrupted and I had to delete it.
If somebody could enlighten me on this application, I'd be most grateful.