Or use a 17" and a 128MB 9550Pro and a have a decent $400 game machine.
Although, to be honest, I think game machines really do need a full 1GB of RAM. The big MMOs (WoW, EQ2, MxO and COH) all do much better, and so do the big-name shooters.
So, OK, a 17" CRT, a 9550 Pro, an extra 512MB RAM...