Advice for Picking Between HP dv6t and Dell Studio XPS 16

I've posted before, and I want to thank folks for their help already. I'm looking to order a laptop today, but would like some advice on whether I should get one or the other. I'm a student and in the military, and not a gamer. I'm still looking for speed, and most of the laptop's duties will be multimedia, Internet, and similar programs (I think the most robust will be Office or MATLAB). I've also been looking for something that will last about 2 years, at which time it will either be time to change laptops and/or upgrade my desktop. That being said I'm looking at the HP dv6t Quad Edition and the Dell Studio XPS 16, both with the Core i7. I was also looking at the Asus G51J-A1 but that is turning out to be out of my price range. The Dell is also quite a bit more expensive than the HP, which is why I'm looking for advice, particularly from users of similar components. The Dell is coming in around $2400 shipped and the HP is around $1500 shipped. Therefore is the $900 difference worth it and will it last? Here are the major differences:

Screen: 1366 x 768 LED (HP) vs. 1920 x 1080 WLED (Dell)
Memory: 1066 MHz (HP) vs. 1333 MHz (Dell)...both are DDR3
Video Card: Nvidia GT230M (HP) vs. ATI Radeon 4670 (Dell)
Hard Drive: 320 GB 7200 rpm (HP) vs. 256GB SSD (Dell)
Sound: Realtek probably (HP) vs. Soundblaster XFi (Dell)
Battery: 12-cell (HP) vs. 9-cell (Dell)

Obviously, the Dell is a superior machine, but for my needs, and the time I intend to use it, is it worth while to spend extra now, or get the cheaper one, and then use that extra money in 2 years for a different laptop? I assume I could also upgrade the HP to a SSD when prices come down, correct? Does anyone have experience on how long batteries will last? How long will a 6-cell battery vs. a 9 vs. a 12, etc. How much non-gaming performance increase will the Dell have over the HP? Any other thoughts or advice? Thank you in advance.