Dell have the new Sandy Bridge laptops coming through (albeit on preorder)

For ages my g/f and I agreed we'd get a 13" Macbook Pro once the Sandy Bridge chips went into them but now Dell have released the XPS 15" L502x and XPS 17" L702X and I'm sorely tempted.

I can get the 17" for £1300 inc 1920x1080p screen, GT555M BD drive, TV card.
15" is £1050 inc 1920x1080p GT540M, no BD, just DVD and no TV card.

Both have the Sandy Bridge i7 2720QM processor

Given these prices I think the Macbook, apart from its portability, isn't worth it. Should I twist dell's arm to give me a 15" with BD drive or just go for the extra size of the 17" and take the shoulder breaking hit to get the better graphics performance?

It's a shame they don't offer the GT555M on the 15" cos that would be decision made. What do people think?