Linux does work with VirtualPC.
You just have change the X video mode to 16-bit color because the VPC emulated graphics card doesn't like true color (can be done from GUI or by editing xorg.conf) and add "-- i8042.noloop" to end of the kernel boot parameter in menu.lst to get the mouse pointer to work.
Those steps above should take all of thirty seconds.
Still... why VirtualPC?
Unlike VirtualPC, there are several of other virtualization products that all have been optimized for a varity of Linux guests.
The cursor in Ubuntu 7.04 does not work in Virtual PC. Ubuntu 6.10 does not have that problem. It has the 24-bit color issue, but that can easily be worked around. The mouse problem in 7.04 cannot be worked around.
As for why Virtual PC, it is free, it supports hardware virtualization and it is readily avaliable. I would really like to use a Virtual Machine that has all of that with SMP support as well.