I know this is an old post, but just in case someone else stumbles across it like I did, there is an easy work around to get the selectOneRadio onchange event to fire in IE. I found this on a different forum and it worked for me (also still works in Firefox).
Add this to the control:
onclick="this.blur()"
[Message sent by forum member 'jtkehoe' (josh.kehoe_at_fblfinancial.com)]
http://forums.java.net/jive/thread.jspa?messageID=391500