First of all, I'm assuming you want a notebook for portability. That beast is hardly portable. I mean, you could move it around, true, but I'm not sure it'd be something you'd enjoy pulling around. But, if you want to spend your money on it, I'm sure you could get some decent specs on it.
Dell overprices their RAM upgrades, so if you can, spend the least you can on the RAM and buy your own set at another site. RAM in notebooks has got to be the easiest thing to upgrade, just pop off a lid and your there.
There's a Santa Rosa chipset (Intel C2Ds) out for notebooks now (Increased the FSB of notebook processors to 800Mhz), you might want to look for that. Model numbers are odd, i.e. T7100 1.8Ghz, 7300 2.00Ghz, 7500 2.2Ghz, etc. Along with Santa Rosa are the DX10 mobile GPUs from nVidia. The 8600m GS and GT + 8400m GS and GT. They aren't the strongest cards though, the 7950GTXs are the most powerful GPUs as of now.
Personally, I don't think it's worth the money. I'm sure there are other laptops out there with great performance without the huge price tag. The Macbook Pro is an example. Except the one thing I don't like about the Macbook Pro that the above poster listed is that it still has the X1600 Mobility, even though it's a 17" sceen. Dell has a laptop (E1705 I think in the States) that can be configured with better specs than the Macbook at 17". Might be cheaper if there are Dell coupons you could use.
Well, in the end, know that a laptop will run hotter than a desktop and getting a really big laptop (17"+ IMO) will get really hot. If you're looking for a big laptop like that, I'd think you're better off getting a desktop computer.