I had an Intel webcam that did NOT like running under VPC. It was recognised, and was there, but the hideous slowness of VPC made its real use prohibitive. If you're going to be running XP in the VPC, forget about it.
There are two collections of Mac drivers for Windows webcams (if they have open drivers, or their chipset is open, unlike my Intel one was), but I don't remember their names off-hand. Shouldn't take much searching in Google to find them.
I recommend using them in OS X and giving up on the VPC idea unless it's ESSENTIAL.