I've got a SCSI pioneer DVD/CD drive that rips very fast. cdparanioa (similar to EAC i think) usually finds no errors to correct. But yes i've heard good things about plextor drives too.

For CPU it's just a matter of the faster the CPU, the quicker it will encode. LAME VBR --high on my 1.4 GHz Athlon encodes much faster than realtime..

You won't need much ram, 8Megs + whatever your OS needs should be pleanty.

IDE bus speed shouldn't matter, any mode that does DMA should be fast enough.

For ethernet you can either plug it into a hub/switch, or plug it directly into your PC with a cross over cable.