I'd be sure to tell him, but I agree it would be best to tell him when foreplay is heading that direction. It will be a major turn-on for him, and can only benefit the experience for both of you.
That said, if you're a 24 year old virgin, there's likely a religious or other personal choice issue involved. You need to decide for yourself a few issues here. For one...are you comfortable with being a virgin at this point in your life...if not, go for it. If you are, and would prefer to remain that way until marriage or what have you, then don't give in now...you've come farther than most.
Anyways...my $.02.
