I got Dell's P4 2.4 GHz laptop with 15.4 wide screen display. CD-RW/DVD combo drive, 40Mb harddrive, 64Mb mobile video card and 512Mb ram. I had no problem with any game or emu to run on it, except wide screen might in some cases seem very strange and produce strange results.
I was thinking also to get an old Dell Inspiron (best laptops IMO) laptop with P or P2 proicessor in range of 200-366MHz. Those laptops are durable, and they come with CD/floppy drive combo which you can replace with extra battery (for longer play
)
One that I might buy later from my employeer has 15" screen (used to be mine laptop
).