Google around, you can find some dashboard camera mounts. It really depends if you want to mod your dashboard too, how it's shaped, and the like. But it shouldn't be too difficult. Also, there's always the option of a backseat camera. I setup a tripod in my back seat once and it worked pretty well. At least until I took a curve a bit too sharp and it fell over! Some weights should fix that...
As for using a laptop, it really depends what type of camera you have. I wouldn't bother looking for one with analog (RCA) inputs. Perhaps simply get one with firewire. Though digital camcorders today are quite nice. My Jazz can record 2 hours of 720p video on a 4GB card.
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Primary- i7 920 | 6GB RAM | 9800GT | 160+160+500GB
Secondary- Athlon X2 4200 | 2GB RAM | 7600GT | 80+250GB
Netbook - Atom N280 | 2GB RAM | GMA945| 160GB
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