I posted the message at the bottom a while back while looking for answers. A reader replied with a solution, and I have received enough email asking about this that I figured I'd just post the solution here.
To get the Netgear PS401 wireless card to work in a notebook/desktop PC, download the latest drivers from Netgear's website for the MA401 card, then open the NETMA401.INF file in notepad for editing. Change every instance of "MA401" to "PS401" and save the file. All you need to do now is manually install the drivers for the new card (choose the "have disk" option and navigate to the folder where you saved the driver files). (I used the WINXP folder -- the drivers I downloaded have the line "DriverVer = 06/29/2002, 2.0.2" in that .INF file)
After installation of the driver, the card should function exactly like a MA401 and allow you to connect to your wireless network.