I think that if both participants class something as sex, and went into the act as sex then you are not a virgin. But the concept of what constitutes sex is entirely different depending on who is partaking in it. For example, I was in a situation with who was, at the time my best friend, involving touching each others genitals and sleeping naked/almost naked - I can't remember - together (just to clarify, he had made me deliberatly drunk, that's not my normal behaviour), and we did not class that as sex. However if we had been two lesbian females then we would have classed that as sex. I consider that I lost my virginity with my ex-boyfriend though penatrative sex, however we would have equally classed anal sex with me taking, or me giving him anal with a prosthesis/strap on, or had we been two FAAB's 'lesbian' sex. So yes, if you both consider it to be sex, then you have taken their virginity, in my opinion.
I agree that the world is too hung up about the existance of virginity. I thought that I would feel somehow different, or be somehow different after having sex, but although a highly enjoyable, intimate, close act, it does not change who you are as a person, your level of purity or anything else about you, physically or mentally.