I bout an Asus ROG somethingsomething for about 1400.
Q820, 16gb ram, 1tb hdd + 64gb ssd, GTX 460M.
I would not suggest a 15.6" like I purchased though. It really is big.
I would really suggest aiming for a 14".
Laying down some base stats...
4 core @ 2ghz (i5, NOT i7! i3 would be good even!), 4gb ram, HDD doesn't matter too much (cheap as chips), but SSD if you can afford (I got a 64gb SSD @ $80, but my deal was really great), 400 series is good, but remember that you want something >420. As for ATI, you will have to compare yourself (it is pretty easy just google).
You should be able to get something decent for $1000.
Remember to check Ebay. There are a lot of 'configure your own' on there, that are way cheaper than manufacturer or from shops.