I've almost had no experience rigging but would it be easier to set the mouth to the center than to the side then making blendshapes accordingly?
Imagine rigging the face and the skin weights...

No worries with that setup you got planned.

Maya still works fine with my old 32bit athlon xp 1800+ , 1gb ddr pc2100, and ATI AIW 9600xt.

Since I'm a student and don't own a portable drive, I just email individual files to myself, if the attachments aren't too huge.

absolutely wonderful. Great job there