my suggetions come from me getting my girl slowly into gaming, and here's what i've found:
A) she seemed to like to drive around in burnout paradice city, even tho she never done any races etc, she like to drive around the town.
B) she likes Zak and Wiki, she likes the cartoon style and after getting her to think more logically, she's kind of addicted to it, even tho she gets stuck and sometimes annoyed. she still plays it
C) she dont mind the occasional go of guitar hero on the slowest speed. she still rubbish, but at least she has a go.
D) Probably the most effective games are tv shows like deal or no deal, who wants to be a millionarre, telly addicts etc...
i think wii games would prolly get her into games the most, as its easy to do. move around and move character etc... but seeing as your on pc, i'd say go with "D"
anyway. good luck
