Hi and welcome to daniweb,
The KEY to this is your own statement below:
I'm currently on a network and it has a LAN P2P spreader that has infected all 6 computers on my network, including media center PCs. Needless to say, when I reinstall my OS I simply get reinfected within the week.
We can clean your computer until "the cows come home" but it WILL continue to get infected if the entire network of computers is infected. You are not going to do any good just cleaning yours, they ALL have to be cleaned OR you have to disconnect your computer from this network and not reconnect until the entire network is clean. There really are no single computer options here. If you know absolutely the entire network of computers is infected then you have to clean them all to be completely free and clean.