Posted for archival purposes for those who need it.
The Linksys WPC54G v4 PCMCIA wireless card, which I got in a kit with a wireless router, appears to not work with WPA under XP SP3. Seems to be an encryption problem. The card is suppose to only be used under the Windows Zero Config utility only, although a Linksys utility does come on the CD. I've never used the utility.
This thread at the Linksys forum discusses the solution:
Which is to use an Inprocomm driver. This card, and only this version of the card, v4, has that chipset.
Linksys doesn't have the driver on their site.
I got the driver here:
I downloaded all of the separate files and pointed device manager to the files when I did an update driver for the card.
The driver was accepted, and WPA worked from then on. There was no need to uninstall the card first.
whosbest54