Just a quick note to say that the Dell PowerConnect 2708 is fantastic. I was able to get a sustained 112MB per second (that's 112 megabytes, not megabits) between two Core 2 Duo machines (Vista/Windows 2003 Server R2) using PCATTCP. That means that the connection is completely saturated and that the Dell box is switching at the maximum possible speed. Sweet.
In more real world numbers, I was able to get sustained 2.2GB/minute transfer rate using normal Windows file sharing copying from Vista to the server when the file copy was initiated on the Windows 2003 Server side. That's close to the maximum read speed for the source disk, so presumably the disk was the bottleneck and not the network.
Oddly enough, when the file copy was initiated on the Vista side, I only got about 1.2GB/minute with the same file being copied to the same destination. I can't explain that.
[Edited 8/27/2007 to add information on the read speed of the disk.]