If you can only afford one bike get a cyclocross bike. It is the most versatile bike. Let the shop know that you might want to race it as a road bike and they can set it up with the proper gearing for riding road; but, be certain what you want to do with this bike - If road racing is just a thought in the back of you mind and you intend to take it off road a lot, tell them that and don't try to gear it for the road.

It will never make a GREAT road race bike. So if you get into road racing you will inevitably buy another bike.