Slow network transfers from Server 2k3 to win7

[Procyon12]

i installed 6 Windows 7 Pro computers on a network and files transfers and share browsing is painfully slow from any of the workstations downloading off a 2003 DC. the existing XP machines work perfectly fine, and the W7 workstations can share off each other fine.

i turned the firewall off, and havent even put any AV yet? ideas?

these are all Dell Optiplex 780s from the same 'batch' you could say and have the dell factory image...