There's another way to see if you have the X50 Basic Click on Start > Settings > System Tab > System Information applet. If your Processor speed isn't 624MHZ and your ROM Size isn't 128 MB then you definitely have a X50 Basic.
You can get either a
Compact Flash or
SD WiFi card for your Ax. Just be sure the card works with Pocket PCs. There are some cards made specifically for PALM PDAs.