I have the same problem on a newer computer even though it have a port.
It's a HP Pavilion that I managed to get running with WinXP.
BUT: Since the computer don't have a com port I bought a (two different actually) PCI card with an parallell port .
The problem seems to be that it get's a high IO adress like $BC00. Or maybe it's the lack of BIOS support for COM and LPT ports.
I can see it peeking the adresses. But most programs have problem finding it.
Suggestions anyone?