Buy HP Pavilion dv6700t series, HP Pavilion and Compaq Presario Notebook PCs and Laptop Computers direct from the HP Home & Home Office Store
^= Click on Customize and Buy, then add the 8400GS or change a few other components around, and you are good to go.
But seriously, I can even work with 300dpi pictures at 20" x 20" on my Eee PC, so I don't suppose you'll need such a monstrous computer just for Photoshop. As for gaming, if you don't intend to play anything past 2004, then that laptop from HP can last for a few years. I myself barely play anything past 2000. MGS2 on the go FTW! (okay, I lied. It wouldn't run MGS2 that well... but what the hey?)