Networking with a computer with Windows Professional 2000

I have two Gateway Computers, One has Windows 98 Installed
and the other Windows 2000 Professional. The are hooked to
a Office network.
I have marked all Files and Drives on both machines as
Share.
On the Machine using 2000 I am able to access the C Drive
and files on the machine with 98, however I am unable to
do the reverse on the machine with 98 I cannot access the
files or drives on the 2000 Machine.
How do I Setup and configure the 98 Machine to access the
other Computer Files and Drives?
Any help will be appreciated