Just buy 2 bikes. Get a cheap fixie from http://bikesdirect.com, then save your money to buy a decent road bike.

It's a royal pain in terms of both time and money to convert a fixed gear bike back to a road bike. Yes, it can be done, but it's easier to have 2 working bikes than 1 bike and a bunch of random parts, especially since buying a decent parts group and wheelset separately can cost almost as much as a pre-built road bike.