Which handhelds will work with MarkMyScriptures?
MarkMyScriptures is designed to work with Palm devices having Palm OS 3.0 and above, including:  

If your Palm device has the following features, they are supported in MarkMyScriptures:

Which handhelds will work with MarkMyScriptures CE?
MarkMyScriptures CE is designed to work with Pocket PC devices and CE, including:  

Specifically, the software will run on ARM, SH3, SH4, and MIPS processors for Windows CE version 2.0 and later, Pocket PC, and Pocket PC 2000