Hi all, I need help switching my refresh rate, I just can't seem to figure it out.

Current display mode: 1440x900@60Hz in 24-bit.
What I want: 1440x900@75Hz in 32-bit.

I tried going to http://www.sh.nu/nvidia/gtf.php to get a modeline to put in the xorg.conf, but it didn't work out, I just got told that Ubuntu was going to run in low graphics mode because it couldn't detect my settings.
The modeline I tried was "Modeline "1440x900_75.00" 136.49 1440 1536 1688 1936 900 901 904 940 -HSync +Vsync" and to be honest I'm not sure if this is accurate. I put this piece of information in Section "Monitor" of my xorg.conf and that's when it went bad.

Display Adapter: ATI Radeon 9600

xorg.conf contains:
Section "Device"
Identifier "Configured Video Device"
Driver "fglrx"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
Defaultdepth 24
EndSection