I\'ve had good luck with Lexar cards on my 5500. Stay away from sandisk SD\'s (there CF\'s are ok).
However, keep in mind that flash media has a limited number of write cycles (usually about 100,000). That may seem like a lot, but if you end up with a heavy load where your system is swapping a lot, you can use up those write cycles fairly quickly. If you want to use your zaurus for anything heavy enough to require a swapfile, then you may want to investigate getting a microdrive for your CF slot. These are faster, and don\'t have the limit on the number of writes you can do.