I am about to buy an HP 6000T laptop, comes with a 7400 Go, 12 cell battery 2 gigs of ram Core 2 duo ect for $1,100 once my desktop is to be sold.
The crux of the argument is that you cannot upgrade the video card/processor/mobo unless you are EXTREMELY good at it and know exactly what you are doing (even then it may not be possible).
With the 7400 Go my laptop will still be able to function fairly well on most games with high graphics on the ones I play (C&C 3), UT2k4, and that is pretty much it.
All in all, laptops are nice, but if you are getting it for gaming (I am not due to the fact most games these days are getting lamer and lamer IMO and I have lost most of my need to play them so I am solely going after a nice laptop that can play movies well and the occasional game and will last me for 2 1/2 to 3 years)
Thats my $.03