Rhively, e-learning may be a decent place to start, but it's no substitute for the give and take with a human instructor and classmates, who'll make for a livelier course and help flesh out the material.
Listen to Bob Vincent, he's giving you solid advice.
Unless you're going to be in Aruba a long time, why would you want to waste that valuble time on the confined water portion of the class. Even if you decided to go that route, consider that you'll be rushing to get lot's of practice and classroom learning squeezed into a short time.
Consider a referral course where you do the classroom and confined excercises up here, with plenty of time to learn it solidly, then you do your 4 OW dives in Aruba 2 per day. By day 3 you'll have your c-card and ready to explore the reefs with a local dive charter.
It's still warm enough if you start now, to do the course locally, with the OW dives in Dutch Springs, or Rhode Island, towards the end of September while it's still fairly warm.
Either way, you'll end up a better diver, with more opportunity to enjoy your Aruba vacation.
Good luck and have fun whatever you decide. dF