ever thought about using BitTorrent as the distribution method? There's a good community around this site and I'm almost sure this would work wonders for your bandwith.
I built a HTPC recently. It is aimed to provide me with TV watching capability and an occasional Diablo II session plus some OpenOffice.org ... so far the nForce 2 integrated graphics was okay. But ...
I have been plaqued by bad luck since I built my HTPC
The configuration is:
Asus A7N8X-VM 400
AMD Sempron 2300+
256MB DDR 333
Leadtek WinFast PVR 2000 (TV tuner)
a generic 300W PSU
a ...