There are
"PCI to PCMCIA" PCI cards, but I personally would just get a 4 port
PCI RS-232 card. Your application won't know the difference and you won't have to worry about incompatibilities between the PCI card and the PCMCIA card.
If you do decide to go with the adapter, just google
PCMCIA to PCI adapter and you'll get plenty of results.
Ed

Ed Dickens - Certified LabVIEW Architect
Lockheed Martin Space
Using the Abort button to stop your VI is like using a tree to stop your car. It works, but there may be consequences.