[quote=icicle]
I would recommend taking a "pre-determined system" and simplifying it, because making a whole new one will not be an overnight task, to say the least. I do not have experience in tabletop roleplays at all, so take my advice as a suggestion if that is an indicator of validity.Also, for dice rolls, you can google a random number generator and set parameters for the probability you want. On you can set lowest limit(1) and highest limit(6) to make a d6, or lowest limit(1) and highest limit(20) to make a d20, so on and so forth.
[/quote]

Cool thanks! But what I meant for a system was to use Fallout's own S.P.E.C.I.A.L system. Of course I need to tweak it a bit, since it is already fit for a tabletop game. It is an offshoot of GURPS.