The card is a radeon 9550, 256meg, and dual out, so it can certainly handle what I'm asking.
I am only getting 1024x768 on both displays, even though I have the correct entry in XF86config.
Here's what I have for this particular entry:
Section "Screen"
Identifier "Default Screen0"
Device "Generic Video Card0"
Monitor "Generic Monitor0"
DefaultDepth 24
(removed extra lines to keep the post short)
SubSection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600"
EndSubSection
EndSection
And the same for the second screen/display/monitor etc..