hell, even a 945 board would do just fine in sff if your not playing halo heh. I use my GMA900 laptop for all my everyday use, some graphics work and to play back all my .h264 anime content on my hdtv.
It did it fine with a 1.7 ghz dothan, and does it even better with a 2.13 ghz dothan =D. so even if you stick a e4300 or e2xxx in there,its gonna be fine.
if she wants to game, consider picking up a hd2400/2600. they are really cheap, passivly cooled and have hardware video playback. they can of course also run most games at a half *** decent level.
im in the same boat you are kinda. looking for a good cheap mATX. im looking at intel branded 946 boards honestly.