When I try to connect to a shared drived on a Windows 2000
machine from a Windows 98 machine, I am prompted for a
password to connect to "machinename/IPC$" - the password
requested is not one known to me (i.e. - not an account on
the machine, etc.). The Windows 98 machine does "see" the
W2K machine - i.e. - it shows up in the Network
Neighborhood. So what am I doing wrong? Thanks.

Try to join the two machines in the same work or domain group and then log in the Win98 machine with a user defined in the 2000 machine.

The machines are in the same workgroup. Windows 98 is not
giving me a "normal" username/password screen - I am
getting just a password field, the resource/server name
shows up as "machinename/IPC$"

Any other suggestions?

When rebooting win98 and ask you name and password, join with administrator name account and password of the 2000 machine.