Screen Resolution Question

[Eric B]

I have been running Hoary since October.  Recently did some changes, 
and moved some stuff back and forth.  Now the screen resolution in 
KDE is stuck at 640x480 <nearly unusable and quite ugly>  The Desktop 
properties selection is no help, it offers me 640x480, and 320x240 
<even worse>.

I'm not exactly sure what I did to make this happen.  I made some big 
changes to the system, and didn't do it incrementally like I should 
have.  I don't want to reinstall completely, and lose all of the 
stuff I have on the system.  I can't seem to find the equivalent of 
"Hardware Manager" to reinitialize just the video card, etc.  I 
suspect I can edit a file and force it to the higher resolutions, but 
have no clue where to start.

Any hints on where to start looking?  Where does KDE look to find out 
what resolutions are allowed, etc?

Thanks,

Eric