A quick check using "Search the forums" immediately locates an extensive thread about this:
http://www.hpcfactor.com/forums/forums/thread-view.asp?tid=8389&posts=266
Reflashing the 900 to CE 4.2 .net is free and relatively easy
(and may not even be necessary to run a Linux distro
).
Please make use of our search utility for questions about the 900, including your other recent thread, the topic of which is also covered extensively in these forums.