Windows XP slow browse of 2000 Server or 2003 server peer to peer

Hi,
I have a small network running 2000 server for file server and network
browsing is very slow.
takes 3 - 5 mins to open shared folder or drive on 2003 server.
I even loaded 2003 server to see if problem was in the server.
I have reloaded two Windows XP workstations hoping to fix the problem.
I have a netgear FVS318 for a switch and router.
all workstations have the DNS pointed to the server.
found if I changed the nic speed 10 -100 or 100 - 10 the browsing
worked correctly but shouldnt have to do this every time I want to
access the server.
any ideas

Apples