I'm really torn between these three models. Doing some casual AutoCAD, light/mild gaming and some business. I want a reliable, long lasting laptop. Would like good battery life 3 hours of over but it's not a deal breaker. Quad-cores seem to eat up the battery more than duals, so any input between these three would be very helpful. Prices are about $550-680-750 between the three models. I see some good reviews on them but some say the screens are not all that great and others say they are. In your opinion, is the price difference warranted for these models, or too much? Or should I forget about these models entirely? Thanks in advance.