Microsoft has Visual Studio 2008 Pro available for a 90 day trial period (
Visual Studio 2008 Trial Downloads).
I have it installed, and I am tinkering with it to write an app (
right now I've just started, so I'm going to read from a file, and write to a file, and work out something to display the contents of the file).
Someone suggested I look at eBay or Craigs List to get a copy for when this expires.
I have seen it for the low $100s, and student copies (that I understand are fully functional) for a little less.
I am working on putting something together in C++ (I know C, so this seems like the easiest to start with).
If anyone else has input on developing for our Windows Mobile devices, please add something here.
As I use Visual Studio, and if I run into anything interesting, I'll add that here.