Hi, I installed debian 5.06 on my Mac ibook g3, I had the same problem, the interface is only on a portion of the screen (about 70% x 70%) of the size of the screen. The screen is configured for 800x600, there is no another resolution, so I suppose I need another driver. here is the lspci output ; vga compatible controller : ATI technologies Inc Rage Mobility M3 AGP 2x (rev 02).
secondly, If i couldn't install linux on this mac, can I retrive or reinstall ??? the mac OS ?? thanks for any idea best regards bela