While in OS X you can change the Macintosh HD icon using the traditional GetInfo/Copy/Paste method. To change the XP partion icon I downloaded CandyBar from Panic. I had already downloaded Carlito's substitute HD icons. So, I just dropped his XP HD icon into the CandyBar well for Device icons/Internal. Worked like a charm. The new icon doesn't show up in the boot choices screen, but NBD. Looks great on the desktop!