screen resolution problem


Hi there !

my problem (if it is one anyway) is as follows: the monitors control panel does only present a few possible screen resolutions to me and I don´t know how to change that. The preferred resolution wuld be 1280/960@75 or 85Hz. It is no problem in 9.1 or 9.2 (the latest beta). I am now running with 1280/1024 @ 85 HZ but don´t like this kind of black frame around my desktop. OK, I could adjust the display itself, but if I´d do this, I´d have to switch this again and again when booting into 9.1 and vice versa....
My configuration: PowerMac G3/MT 266, 512MB RAM, ATI Rage 128 PCI, some HD´s, a Keyspan USB Card and a Fujitsu-Siemens C992 19" Display.

If anyone got an idea and would post it, I would appreciate that very much.
Thanx in advance,