Doug, until Brent comes up with "clubjaguar" check out
http://www.jag-lovers.org/. Classic Motorbooks also has some great XK books if you haven't seen them. The Xks are popular concours cars and are often at the larger concours events (Hershey e.t.c.) Keep your eye out for the Jaguar "Automobile" special on Speedvision.
Hope this helps,
Jordan