Windows 2003 domain (upgraded)

Greetings,

Recently I have upgraded a Windows 2000 domain to Windows
Server 2003. I did this by using adprep and then
dcpromo'ing a new Windows 2003 member server up to be a
DC. I then moved all of the FSMO roles to the new server
and made it a global catalog. The old server is still
online, but is on its last leg and about to be retired,
thought it is still a DC/GC for the time being.

Now my Windows 98 domain clients are not able to change
thier passwords. I believe the error message is that the
device is not available. Previously, we have not needed
the DS client, and therefore it is not installed. Due to
the amount of 98 clients (we are in processing of moving
to XP) we do not want to install the DS client on all the
98 PC's.

How can I fix this problem so the 98 users can change
thier passwords?