Tell her that a piece of plastic can't take away her virginity. Masturbating is not a stain on her purity - it just makes her know what her body prefers.

I'd tell her to start researching about sex, beyond what she learned in sex ed. As I understand it, most women don't really use vibrators for penetration, but for clitoral stimulation. Make sure she knows she has one, where it is, and what it's for. Bust the myth that every woman has earth-shattering orgasms from penetration alone (if she's one of the ones that doesn't, she shouldn't feel like a failure). Talk to her about birth control options and about foreplay. Some of the fun is figuring out the private things between you and your partner, but if she knows the basics about herself, her body, and men's bodies (assuming she's straight), she's in a better position.