1024x768 is okay, but no lower...in fact, i dont think you can get lower... Laptops generally don't have amazing graphics chipsets in them, so if you had a high resolution, like the ones found on some iBooks and others, (around 1440x900 i think), you would have to run games at that to get the clearest picture, but your system would chug due to such a high resolution.
I think 1024x768 will give the best resolution/performance ratio...for a laptop.