I have a SL-5500. I would recommend getting the SL-5600 if available where you are. The SL-5500 has some memory issues. If you let the battery drain down to nothing, you lose everything unless you have a backup. The SL-5600 has some internal protected flash memory the solves this problem. Also, it has a speaker so you can hear your mp3 files instead of needing your ear phones.
or see if the SL-6000 is available:
The Yopy's are seriously cool but I think the Sharp will be supported more and probably more popular as well. Just my thinking anyway. There is also the
and the Zaurus C860 which is still unavailable at this time.
These 2 models are of the "clam-shell" design. They look like mini laptops. The specs are simple to die for. I hope this helps.