Yes, but why is it waking up? It's not mouse movement, it's not Wake-on-LAN. Is it this damn router?
Update - more info:Today I was using both the Mac and the PC, and I had the PC's shared documents folder mounted as a samba share on the Mac. Before leaving for class, I shut the lids on both, putting both into sleep mode. When I returned from class, I opened the lid on the Mac, which still had the samba share mounted. Immediately, the PC tried to wake up. This leads me to suspect that the PC is attempting to respond to some sort of network stimulus. In this particular case, it's like the PC wanted to be ready to share data with the Mac. On other occasions, it must be the router polling it or something, I have no idea.