I got my X-Lite 4 to answer calls after a little fiddling around, the last step was to tell it what ports to use.

Starting with a standard configuration for X-Lite, Windows 7, and a Linksys WRT610N, all I had to do was setup some port forwarding on the router, bless X-Lite 4 in Windows Firewall, and setup a range of ports in X-Lite 4. It seems to work OK with only two ports. It might be useful for other newbies if there was a basic setup guide for various combinations of routers, desktop OS's, and softphones, but this was pretty easy.