Xbox Live download speeds

Have we ever figured out what is up with the download speeds on XBL? I had hoped to try out the NBA street demo before heading into work, kicked it off this morning and 30 minutes later was at only 34% for a ~600mb demo. Do we know what IP ports the download uses or the protocol? Are other folks seeing this kind of poor performance? For me download speeds have been erratic, sometimes good, but often sub par. Downloads from the PC are super fast, and I can host games with the 360 with no issues as well. I would think MS is just being saturated or throttling the traffic on their side but it seems that some folks dont have these download speed issues.

The Graw 2 demo downloaded well before finishing an episode of Family Guy,
so it’s pretty damn fast here. I think the only slightly slow download was for the
Crackdown demo, but it was still done within two hours.