The config shows the commented out modes option does not contain "1280x1024". Did you add it? Was it removed during testing of your custom modeline?
X should use the highest resolution that succeeds in the Modes option, so it should work to add multiple resolutions there (it also allows you to cycle through them using alt_ctrl_+ / alt_ctrl_-)
"..the triumph of evil is for good men to do nothing."
VIDIA video driver RPMs for Fedora
:: see yum repo at livna.org