I would say anything below 16ms would be plenty. If all she does is word and internet (no movies, games, etc.) 25 ms would probably suffice.
Anyways, the 710N is agreat monitor. 12ms, decent color, and pretty cheap. No DVI, but tht really isn't necessary for her uses (I doubt her card even has a DVI port unless it is way overkill). I bet you could skimp a little more, though that samsing definately will please. I was planning on getting one for my rig, but I decided to wait for a good sale on the dell 1905FP...