Andy, that Dell system should be compared to a MacBook, not a MacBook Pro. To compare to a Pro you should configure a Precision or XPS system. In every case I've tried, for both MB and MBP comparisons, the Dells are between $50 lower to over $200 more expensive.

The D630 only has a 14.1" screen. If you configure it starting with its BEST configuration it already starts at over $1500 and still only has a 1.8GHz processor and a crappy edition of Windows. I can't configure one up now because when I click on a number of the small radio buttons Dell's lovely site produces error pages saying something it wrong with the config.

The Dell machines get just as hot internally, but with their plastic cases you may not feel the heat as much. Intel is the primary culprit for the heat unfortunately - thermal grease application issues aside.