Two thoughts:
First, F all this noise about 3e/4e. 3e isn't a beginner's game - it just isn't. You want to introduce her to roleplaying, not a ruleset. I kid you not when I
strongly recommend Basic Set D&D (the 1983 Frank Mentzer version). Not from some grognard-y high horse because it's cool, but because this is the right tool for the job - this is literally a version of the game that's set up as a tutorial.
You play through a little Choose Your Own Adventure-style solo adventure, introducing D&D concepts one step at a time: mechanics like ability scores, hp, attack rolls, saving throws - none of which have changed that drastically - and concepts like "fight, parlay or flee," NPCs, character motivations, and the element of choice - none of which have changed at all.
Then there's a slightly more "D&Dish" solo adventure, which introduces mapping and some other stuff. Then it's on to the DM book, which has entry-level party adventures to run.
If there's a better intro to roleplaying ever to see print, I'm not aware of it.
Second, if you're looking to induct your lady friend into the hobby, you might be interested in this thread:
http://forum.rpg.net/showthread.php?t=377042