XPSP2 + 2003Server = Poor network performance (?)

Hello everyone, this is my first posting here

I experience strange problem with transferring large files over the LAN
to 2003SP1 Std server.

A bit about the network structure: 100mbit/s w/full duplex everywhere
running on 3com superstack 24-ports switch; Active Directory (2DCs).
DNS is ok (names are resolved), ping to the server and the reverse ping
are always 1ms.

The problem is that the copying of large (15-17Gbytes) files might take
about 4-5 hours (!!!) with average network adapter load at the client
machine about 3-5% (according to network performance tab in the task
manager). Server's adapter is loaded not more than 10-15% (according to
the same tab ))

I've migrated AD from w2000std to 2003 not very long ago... Has anyone
faced this issue? How can I solve it?


Thanks in advance!