I go with the 800x600 on my 15" monitor because I can easily see/read everything while tipped back in my chair with the keyboard in my lap and my feet up on the desk LOL.
I haven't a clue what the refresh rate is, but I never suffer any adverse effects from looking at the monitor unless I spend 3 days straight or longer with a game...then the images are burned into my retinas and I can still see them when I close my eyes.
Speaking of which, I haven't played a game since Wizardry 8 was released. I need to go game shopping or go dig through KHaN's and see what he has to play.