I have a core 2 duo e1505 that I'm using for chasing. I highly recommend you have a bluetooth option added to the laptop as this was not a standard feature when I ordered mine. Although I didn't have any bluetooth devices at the time, I now connect both my cell phone and gps over the bluetooth interface, so having built in bluetooth is very nice (as opposed to a USB dongle).
The e1505 is a wide laptop with a wide screen format. I have no problems fitting it in my van though. The screen is definitely bright enough, even in broad daylight (as long as there isn't glare or direct sunshine on the screen). The only issue I've had with it was occasional blue screens during chases causing me to hard boot, losing my GPS logs and consuming about 5 minutes as I had to setup everything up again. I believe this was caused by a compatibility issue between the laptop and my Sony Ericsson phone, however. I haven't seen the problem at all on with my Motorazr v3xx.
As far as general laptop considerations go: Definitely get the 256MB video option as this is a really requirement for Vista, and will let you smooth GRLevel3. Make sure you also get 2GB of RAM. You're going to be taking a performance hit if you don't.