school is just around the corner and it's time to purchase a laptop. i definitely qualify for the education discount/ipod rebate, but i am really just looking at prices now and wanting to get the most out of my dollar. i've been a member of ebay for quite a while, just not very active. i'm concerned that if i do purchase a used computer, how will i know if there is any liquid damage? is there a way to check for this without taking the mac apart? is this just the risk you take with purchasing used electronics on ebay?