I have a 10D and a few L lenses and have test-driven the 20D - very nice. It has a more substantial feel than the Rebel XT, although the extra features are fairly advanced and most people could be very happy with the XT.
Check the Canon 20D forum on dpreview.com for the experts
See the other recent thread on digital camera purchase recommendations -
http://www.flyertalk.com/forum/showthread.php?t=447034 - B&H, Adorama, buydig.com - I've had good luck with all of them.