The answer here is actually quite simple: What kind of laptop do you want?
The Dothan laptop will give you very good performance and a great graphics card, in a very portable package that will be able to last on the road for about 4 hours, and be about 7 pounds carrying weight.
The AMD 64 laptop will give you about 5-20% more performance, and the 17" screen will give you more on-screen real estate, however portability will be reduced as your battery will last about 1.5 hours and your carrying weight will be about 10 pounds.
If it was me who was buying the laptop, I would get the Dothan one because the performance you get with the AMD laptop in my opinion does not justify the loss in portability, after all it is a laptop because desktops with the X800/6800 will easily outperform the best laptops. I also doubt that the AMD would have any significant gaming performance advantage over the dothan, because it is the graphics card (ATI M 9700) which affects gaming performance most.
But really, it is up to you. If you do not intend to take the laptop with you frequently (ie. less than twice a week) then get the AMD laptop. If you intend to take the laptop with you more than twice a week, then get the Dothan laptop. If you dont intend to take it anywhere, get a desktop.