Airport interfering with an RDC connection that works fine..

Greetings all,

New to RDC and this group, so my apologies if this has been covered.
However, my search of the archives did not seem to list the same
problem.

I am running an iMac with Mac OS 10.3.2 with cable modem service at
home, and connecting to a Windows XP box at work.

When I plug my iMac directly into the cable modem, presto, I can
connect and use RDC to operate my Windows box. But as soon as I go
back to running Airport -- no other settings changed, at least by me
-- I get part of the login box on the Windows machine, then the
following error:

You have been disconnected from the remote computer. The connection to
the remote computer was broken. This may have been caused by a network
error. Please try connecting to the remote computer again.

I am assuming it is my Airport set up where the connection "was
broken" but I can't figure out why.

Any ideas?

Winston