integrated ati rage pro not handling vga=791
 

integrated ati rage pro with 8MB video RAM. Running Ubuntu Linux, Grub bootloader. When I try vga=791 after the relevant kernel entry in menu.lst, I get a blank black screen during bootup with "mode not support(ed)". vga=789 works fine - except the resolution is not fine enough for me: this is a 17" LCD screen, and I want the console to be at least 1024x768. I tried vga=790 and vga=773 with similar results (similar to vga=791--i.e., blank black screen during bootup). Have not tried vga=792 yet, since I presumed the higher color depth would be even less likely to be supported. Any tips on how I might make this hardware give me a 1024x768 console?

Thanks, James