To answer the original posters question:
A low spec computer is more than enough man. I have been doing fairly intensive engineering simulations on a PIII desktop. Works fine. I am sure your gf will mainly be doing just research, internet, word processing, and basic multimedia. Any mainstream laptop would do really. I don't think dell/compaq/e-machines, etc. sell Pentium 200's anymore
Just remember, she doesn't play Doom III. She doesn't need to overclock.
The most important thing for her is probably the weight of the damn thing. And of course a decent display that doesn't kill her eyes. Even though I've never owned a celeron, the boot up process aside, what is she going to do to take advantage of the higher cache size in a normal processor?