Win 98 client and Win2k server – slow

I am using Win98se as a client on a Win2k server network. We have migrated from NT4 server. The new hardware is a major step up in performance, however users are complaining thet the system is slow (significantly slower using the fox pro DB). Are there any tweaks in TCP/IP that can help. I would rather change the server settings than all of the clients.
I have had a similar experience using a Win2K pro client looking at a Win98 shared dir.