Like alienator said, your best bet at this point is to go to a bike shop and at least test ride some bikes to see what style suits you. While you are there, try to get an idea of the size bike you might need. Most shops charge for a full fitting but when test riding bikes, they will usually tell you the basic size frame that fits you, that is the frame measures from the center of the bottom bracket spindle to the top of the seat tube.
Buying a bike online is a bit of a shot in the dark for an inexperienced cyclist. Most don't know a lot about fit and about the quality of components. It is also a bit of a shot in the dark for experinced cyclists because you don't have a chance to test ride the bike before you purchase it.
I don't have any first hand experience with Bikes Direct but I have freinds who have bought from them and most of them were happy with their purchases. Just remember that only about 25% of satisfied customer leave a positive review, but 100% of unhappy customers leave a negative review. From what I have seen, BD sells good quality bikes at a good price. Their shipping and communication with the customer is excellent. But once the bike is delivered, customer service is lacking to say the least. If you go with BD, hope that everything is right when the bike is delivered, some assembly required.