I am thinking about buying a used 20" imac 2.4Ghz core 2 duo (early 2008) from a man on craigslist. He is asking $800, but is offering it with some valuable software preinstalled (cs5, office 10), so it caught my eye. Aside from all of the things to be aware of about purchasing anything on craigslist, I want to know if this particular model is known to have any failures or any issues I should be aware of. I know certain models of imacs should be avoided and want to be sure this is not one of them. I've seen a bunch of chatter about graphics card issues as well as overheating problems, but was unclear exactly which models were most prone. Thanks a lot for any input.