Odd Network Issue.

I have an HP NC8000 that is having an odd network issue.

I installed Debian Etch on it (as well as Ubunut and PCLinuxOS) and
the Internet download speed is horrible using the built-in NIC. I
typically download in 100's of Kbps, and with the NIC I get around
7Kbps.

I plugged in a PCMCIA ethernet card and get the same horrible
performance. If I use the same cable, jack and PCMCIA ethernet in
another computer, I get great performance.

Where can I start to figure this out? ifconfig shows no errors.

Any suggestions?