FC3 dual-head problems

[Harlan Feinstein]

This is the 3rd video card I've tried, and each time FC3 recognizes it, I go 
turn "dual-head" on in system-config-display, put in the details, and nothing 
happens.  Most of the time I log out and back in to make sure X is restarting. 
 A couple times I've done a reboot, all to no avail.  The second screen stays 
blank.

The machine dual-boots to W2K, which has been happy each time to drive both 
displays.

Please help!  Is this a bug in FC3?

--Harlan