I've read several posts that almost answer my question, but not quite. I have a Samsung LN32C530 1080p HDTV I'd like to use as a monitor. I was reasonably successful getting the prior 720p model to work ok using SwitchResX, but I think I just got lucky with the parameters (1360x768@60Hz).
I tried the expected (1920x1080@60Hz) values and "nearby" ones, with no luck. Older 720p params actually work, but I get the same small real estate as the older model TV. Trying values near 1080p always displays an image that doesn't match the screen size and is very jagged which makes me think interpolation is making things worse.
Also, SwitchResX has a bunch of parameters other than H x W ("porch" etc), and I don't know how they all work together.