Minimum Graphics memory requirement for 3D Applications

Could someone tell me what is the minumum recommened amount of graphics
memory for developing 3D aplications with VisAD and for building any
Java 3D
aplications.  I am in the process of looking for a laptop/notebook and
do
not want to cut my self short by sacrificing graphics performance for
portability.  Though I am looking for a lightweight notebook between 3.5
-
6lbs, some of them do not have much graphics memory, such as the Fujitsu

Lifebook S-4542 which only has 2.5MB, but I like that it is only 4lbs,
and
still has an internal DVD.

I am not worried about having a system that can play any of the cool 3D
games, but just want a decent development system.

Any 3D developers out ther using laptops???

Thanks,
Luke