I\'ve got a 5500. Haven\'t used a 5600, but here\'s the basic rundown of differences that I\'m aware of:
Memory: 5500 has 64 meg ram, 16 meg flash. The 64 meg ram is split 50/50 between usable ram, and a ramdisk to install applications in. The 16meg flash is read only, and holds the base system programs. However, you can load in a kernel that has a differenet split, so that you have say, 64 meg ram and no ramdisk, and use your SD card in the place of the ramdisk. This way you won\'t lose all your data upon a hard reset. (Look for rom images that specify \"/home on SD configuration\") This will require that you tie up your SD slot for this purpose, so get the bigges SD you can find.
The 5600 in contrast has 32meg ram no ramdisk, and 64meg flash. Part of the flash is normally mounted read-only, the other part is read-write and is used like the ramdisk on the 5500. Of course, you don\'t lose any data upon a hard reset
CPU: 5500 has 200mhz Strongarm, 5600 has a 400mhz Xscale (pxa250). You might luck out and get a 5600 with a pxa255. The pxa250 has a bug in it, which caused Sharp to have to turn off half the cache as a workaround. This causes performance to be about that of the 5500. There is an alternate kernel you can install that turns off this workaround, and people that have tried it have had no problems, just a significant speedup. My guess is this bug only crops up rarely.
For your other questions:
1) MP3 files: Yes, you can play them off either the the SD or CF cards.
2) I\'ve got a 256meg Lexar SD card, works great. Be careful of the brand SD cards you get, some will give you problems if you use it with one of the /home on SD roms. The problem is that some SD cards don\'t come out of suspend properly, and have to be remounted (PNY is one brand I know of that does this). Some other brands have trouble if you write a lot of data to them at once, esp. with an ext2 filesystem on them (Sandisk cards, esp. older ones, have this problem). I haven\'t heard anyone complain about Lexar cards yet, and other brands such as PNY would be fine as long as you don\'t run them as a /home replacement.
3) Video files would be best played off a CF card, as it\'s faster than SD. Also, you may have better luck with different codecs, that compress better.
4) I\'ve got MaxMame running, it works great on older game roms that were originally for a 1 - 4 mhz cpu, such as Frogger, dig-dug, pacman, donkeykong, etc. Also great for games that are portrate-mode.
As to porting other Linux code over to it, keep in mind that if the app wasn\'t written for KDE, then you\'ll have to do a bit of work (the Zaurus uses qtopia / qt-embedded), or you\'ll need to load up an X11 installation (one method is to use vncserver along with a vncviewer for qtopia). Console apps will port fine. Also, SDL apps should port easy, as there is an SDL library implimentation available for the Z.
So, in summary, the 5600 has a faster cpu, which may or may not make a difference on most applications (unless you load up a \"special\" kernel, and/or luck out and get one with a pxa255 cpu). The 5500 has more ram, but in it\'s default configuration you don\'t see the extra memory, as it\'s used for a ramdisk. And the 5600 as better power management and a bigger battery.
Hope this helps...
--derek
