There are lots of manufacturers that make "gaming" notebooks, some more
successful than others. The top right now are Alienware, Falcon Northwest,
VoodooPC, and Dell (the Inspiron XPS Gen 2. Nay sayers look here:
http://www.hardocp.com/article.html?art=NzU3)
The screen size is really your preference. Not every game supports
widescreen so you might see black bands on the left & right sides (like
watching 4:3 TV shows on an HDTV.)
The video card is what makes it. The ATI Mobility Radeon 9700 and above are
the only suitable ATI graphics cards that come close to desktop performance.
The new NVidia 6800 Go is insanely fast for a notebook GPU. Their 4xx Go
series are not good.
The Dell Inspiron 9300 (the non-gaming version of the XPS) can be setup with
a 6800 Go, 1.6 GHz, 60 GB HD, DVD writer & 1 GB RAM for $2016 after this
weeks coupon.