I started just like -- did a course at a local shop before a vacation, and I'm completely sold on diving now. And not just myself -- my wife and two oldest children are avid divers, and the younger two kids can't wait to get their classes, and it's become a great family activity!
I strongly advise against the on-line e-learning route. Get a course with an instructor that is recommended by someone you trust (If you tell us where you live, you'll get great recommendations from this board!). I'd go a step further and suggest that you not only do the course at home, but also that you try and schedule at least 1 local dive outing after your certification, with a more experienced local diver if you can. The more experience you have prior to our vacation, the more you'll enjoy yourself while you're there!
I'd also recommend that you spend some time reading once you're certified. The book "Diver Down" is a somewhat scary, but in my opinion, essential book for new divers -- it takes real world accidents and analyses what happened and how the accident could have been avoided. It can be scary -- so if reading about bad things happening to others turns you off, avoid it -- but it will teach you a lot about how to think about diving.
And read these boards -- this community can be a bit pugilistic at times, but most folks here really do want to help people be better divers.