I’ve written a little C# program to help me debug projects that use the API firmware for the XBee series 2.5 radios rather than writing packets by hand with X-CTU, which is just painful.
As it may be use to someone else I have posted it on my website, where the most recent versions will be kept.
http://www.babryce.com/xbeedebug.html
If it blows up and crashes you can send me a PM about them.