Networking speeds different on OS X & VMWare XP

We just purchased a few iMacs for our business. We have them set up as a Boot Camp partition, then inside OS X, running VMWare Fusion (XP). The iMacs are connected to a PC network via ethernet, not wireless. VMWare is set up to Bridge the network connection (the only way we could get XP to connect to the network). We are all on T1 lines as well.

The problem we're having is to do software updates on the Mac side, it times out, yet we could download the entire XP SP3 patch in one swoop. To get the Mac updates to finish, we have to stop, then start the download around 4-5 times.

Does anyone know what would be causing this?