determine X windows version from command line

[Steven Friedrich]

I've been massaging UberMon for SuperKaramba for my FreeBSD systems.

I'd like to be able to run a command that will yield which X window system is 
installed and what version.

I've done it with something like startx -- -version, but this is problematic 
if X windows is running (which is the scenario I need it to work in).

Even then, I'd have to grep for "XFree86 Version" so it isn't a general 
solution that would work for systems already switched to x-org.

Any deas?