The forth item. And until you run benchmarks the 4670 should beat the 4650 by a smidge. The ATI vs. Nvidia may find one outperforming the other depending on the game used in the benchmark. So it may come down to whether you want Ford or Chevy (uh, ATI or Nvidia) for the graphics.
PS. Remember that laptops are not the best idea for game platforms. Shorter lifespans, no battery life, etc.
Iam going to buy a laptop and i have 4 choices so i would like to have more opinions to help me to decide which laptop would give better performance when playing games.
1- Dell Studio XPS16 ( processor i7 quad and 1G ATI 4670 dedicated) $ 1179
2-Dell Studio 17 ( processor i7 quad and 1G ATI 4650 dedicated) $ 1124
3- Toshiba Satellite A500-ST6647 ( processor i7 quad and 1G Nvidia GT 330M dedicated) $1149
4- HP DV6T Quad Edition ( processor i7 quad and 1G Nvidia GT 230M dedicated) $1019