Okay, let me say this.
YOU CAN NOT GET AIDS IF THE PERSON YOU'RE HAVING SEX WITH DOESN'T HAVE IT.
There is no magical property of anal sex that "causes" AIDS. If the person you're doing it with has no STDs, you can't get any STDs from them.
It's the same reason why you can't get an STD from eating your own semen.
Oh, and to answer the topic of the thread:
Women can get pleasure from it, since it does still rub against the G-spot... however, it's from throught he vaginal wall which dulls the pleasure you'd get from it already, making it extremely difficult to actually orgasm from it.