Um...with the combination of long battery life and 3D modelling + gaming, it looks like you're going to have to go the route of a P-M.
With 3D modeling and gaming, you're probably going to want a higher resolution screen; I personally can't stand to do graphics work on a XGA/WXGA anymore. You should try for a WSXGA+/SXGA+/WUXGA/UXGA screen.
For your graphics card, you can either go for games or for work - that is, either a video card made for games (Radeon 9600) or one made for professional graphics work (FireGL/Quadro).
So...with everything said, I would say the IBM t41p is excellent if you can afford it, else the HP nc8000 is also good. You can also check out the ABS zForce F2 and its equilvalents from Internetishop/Cyberpowerinc/iBuypower. The Dell Inspiron 8600 can be had w/ decent options for cheap, but I would be aware of build quality.