samba - Sep 2002 - windows 2000 vs 98 client performance

I am noticing that windows 98 clients perform roughly 10 times faster
than windows 2000 clients on my Red Hat 7.2 server (samba 2.2.1).  Is
there any known reason for this; and is there any way to tune for this
difference?  We have more 2000 users than 98.

Thanks,
Mark