If you are going for New, go over to Dell.com and check out some alienware products for laptops.
Both those you have listed are higher than directly from Dell.
If you don't mind saving a penny and having a refurbished, that is still under the same warranty, then I'd check out Dell Outlet, look for 17 monitors, or you might regret it
The Outlet only has a limited supplies and the deals can change within minutes so be ready to jump at a good offer
Looking on it right now for me, I see 6 laptops, all +250 gig hd, all with 4+ gigs ram, all i3 to i7 processors, all with over a gig of ram on the video card. all 17" monitors too
Looks pretty good selection for laptops, ranging from 1088 to 1235 for this batch.
the prices to vary a lot on the outlet so if you see a good one, jump at it!
Anyways thats my thoughts, saves you needing to go our and spend another 50 to 200 bucks on a video card, and prices seem better than the best buy listed ones you got there.
In my epxerience with brand laptops, Dells run real well, Alien Ware excellent, but Avoid Gateway like the plague :P
just my opinions.