Force win98 to authenticate to domain before use?

Does anyone know of any microsoft or third party tools/applications to force
users on win98 machines to authenticate against a domain controller before
using the machine?

We have a stand alone scientific network with a central domain controller
that all machines authenticate against. We also have some older win95 and
win98 machines that cannot be upgraded because of laboratory hardware or
software dependencies. We still need these machines to enforce/require
authentication to the domain controller before use however.

Any suggestions or pointers would be greatly appreciated.

Thanks.