Display Setting Help

I resently moved my old G5 into the living room, and connected it via VGA to my TV. When I connect it the computer auto detects it, and keeps auto adjusting the screen resolution, and my apple button, and dock are all off the screen. Is there a way to manually adjust the screen resolution?

It keeps giving the screen resolution as 1920x1080 (interlaced)

Which I understand is 1080i, but that is still taking everything off the screen, and I've tried adjusting it from the TV, but then it just makes the projection screen smaller, and everything is still off the page.