Hi,
Vaginal orgasms are possible. Having proper tone in the PC muscle is important for both partners. Another aspect of vaginal orgasms is technique. Unfortunately most men, including myself, probably learned how to have sex by watching porn. In these degrading films the male is usually seen thrusting very hard. Hard thrusting enhances pleasure for the male but often blurs if for the female. In order to achieve vaginal orgasms the thrusts must be STRONG yet SLOW and in a circular motion. It is important to take the sex act slowly like somebody savoring a delicious meal. The circular motion causes the penis to contact the vaginal walls which is what stimulates the vaginal orgasm. Think of the vagina as gripping the penis. Also try not to concentrate too much on the goal of orgasm but think of compassion for your partner. If you can find it a good book to read regarding female orgasms is "The Key to Feminine Response in Marriage." Most of the techniques I have described are found in that book and they do work.