When Viagra just came out, it was celebrated as the solution to all of men's sexual problem,but like most solutions, it created a whole bunch of new problems.
One of them is that many men came home proudly to a partner who didn't really want to have more sex or have sex that last longer. A lot of 60 year old women felt pressed into having a lot more sex now that the physical part of it was solved and weren't too happy about it at all.
I don't know your boyfriend, but in general, men tend to put a lot more emphasis on long hard erection and orgasms, while for women a lot of time, forplay and intimacy play a bigger role (this is a generalisation of course, not everyone's like that).
I think the best way for the two of you to do is try the Viagra thing once and see if you enjoy it, before you do, tel your boy friend about your doubt and let him know you might not be up to the whole thing. Come to an agreement that if either of you isn't happy and want to stop - you'll just stop.
Also, while using it, vary possition a lot, and use more then just your vagina, this is a cool oppertunty to try oral sex, hand jobs, anal sex, new postures and other things you haven't played with before.
Also - keep a tube of lubrication around in case you get sore and dry.