I have a Zaurus SL5500, running the 3.10 US ROM after replacing the original 2.38 UK one (Pretty similar to the system you are running). Soon after purchasing it I added a Linksys WCF12 compactflash wireless lan card. This was instantly recognised, and set up easily via Settings/Network tool. I also purchased a Netgear Wireless Access Point, and now I can wander around my home, Zaurus in hand, reading emails/web-browsing/copying files to-and-from my pcs/etc. This is a lot more convenient than having it stuck at the end of an ethernet cable. I\'ve even used the Zaurus on my home network from the park outside my home, 200m away.
My advice would be to save up a bit more, and get WLAN CF card and Wireless Access Point. You can use WEP encryption to stop casual war-walking hackers, or a full firewall-mac address set-up if you\'re security-mad. I highly recommend the Linksys WCF12
if you go ahead with this idea.