You replied to me - I was the one asking the question about whether he tried to download large files from other distant servers. Didn't you think that I asked that question for precisely the reason that you are attempting to explain?
Anyway... I tried a download from Microsoft's HD WMV content server - I too am seeing about 350KB//sec - it's Microsoft's pipe that needs Drano or a wide bore snake. I downloaded a 165MB disk image from apple.com and got over 2.1 MB/sec (also on the west coast).
You guys missed my point entirely. I was limited to a 3Mbps download speed per file by Microsoft, but I was able to download multiple files from Microsoft, each at 3Mbps. Obviously the pipe between Microsoft and myself was wide enough, and Microsoft may have been speed limiting individual downloads. It's just an example where greater bandwidth is useful for multiple simultaneous connections.