This company offers upgrades
http://www.pocketpctechs.com/
Silly question but why don't you move the contents of "My Documents" to BIS to save 2MB?
And here's a few more files that I've performed the Odyssey trick on.
Home.exe (I never use it)
Bliss.tsk (ugly green hills wallpaper)
SplashV.exe (the little startup screen that appears after a hard reset that explains the WiFi button operation)