An IA-1 is a K62 based IA with something like 32-64Mb of RAM and WinCE installed on it- has an external CompactFlash slot. Can't be for sure on the memory soldered onto the board- I didn't get too close a look at the innards when Coollogic was visiting them to show off our newest work to them over a year ago.
An IA-2 is a Geode based IA (GLXV, if memory serves...) with something like 32-64Mb of PC-100 RAM and WinCE on a DOC, mounted to a cheap (And I mean CHEAP) color monitor.
The IA-1's got some interesting possibilities- it's a basic PC, for all intents and purposes, with a CompactFlash chain instead of your typical IDE one.
The IA-2's also got some interesting possibilities, but is weakened by the choice of the Geode instead of something else.