As for the Dell E1705, all I can say is that, for $1600 it ought to come with a pair of socks withhandles, 'cause you're gonna bend over and grab your ankles. Integrated Intel graphics, marketting McAfee as a 'plus'... you can do better for the money.
As for buying a laptop off of eBay... You are on your own. Just try to make sure that the person you are buying from has a really good reputation.