Sorry if this has been posted already, a quick search didn't locate anything.

I'm running Ubuntu 10.10 on an Asus K52, and I want to use my 32'' HDTV as a second monitor on occasion, not as a permanent fixture. I have successfully connected my TV to my computer through HDMI, but I'm leery of messing with settings, as the last time I did, with 10.04 on my old Dell Inspiron, it screwed up my screen resolution for a week before I finally managed to fix it. What is the proper way to do this? My computer has an ATI Mobility Radeon HD 5470, and I'm using the FGLRX driver.