Wow. I found the Dell 1720 has this:
* 256MB NVIDIA® GeForce® Go 8600M GT
for $200 more. It also has this:
* 128MB NVIDIA® GeForce® Go 8400M GS
for $100 more. How do those look for the price? They seem like pretty good laptop cards...
An 'equal' model-numbered GS is inferior to the GT. The 8600M GT is a great card. The 8400M GS is a mid range card, but it should still play most games just fine.
8800M > 8600M GT > 8400M GT > 8600M GS > 8400M GS > 8400M G
I would avoid the 7*** series since it's not a DX10 series, and most laptops with these graphics are based on the Napa platform rather than the newer Santa Rosa.
Along with the Dell 1720, you can also consider the HP DV9500T.