Depending on your background in most cases I've found it easier to use
a generic tiny x86 board (e.g. mini-itx, mini-atx, or others) running
Linux or WinCE. If you're used to writing apps that run on operating
systems these will offer you a familiar development environment with
good libraries for IO, threading, etc... and for a very good price
point.

I'm most comfortable working on Linux so for prototyping a headless box
I'll often start off with a Soekris board (e.g.
http://www.soekris.com/net4501.htm ) because they run off of 12V, are
very inexpensive and reliable, then I'll add a compact flash card for
the OS, install an embedded Linux distro (e.g.
http://www.nycwireless.net/pebble/ ), and start developing.

Anyhow, just another alternative to consider...

-Todd

--
http://boatblogger.com/page/thuss