Road Cycling - what kinda bike?

I'm looking to aquire a road bike, for fun, maybe some commuting, but mostly sport. I would be willing to spend $2000 at the max, but the ideal would be under $1000. Should I buy a prebuilt bike or should I try to build my own? What are the negative and positives to each solution? What bike setups would be best? What are all of the parts that I would be required to buy for building my own bike, and what would the price differences be? My preference is a triple.

It is definately cheaper to buy a pre-built but it is not as much fun :) You could buy a build kit and a frame and fork and that would give you everything you need. As far as what frame etc.. go for ALOT of test rides.. you have alot of choices in the price range you are looking at.. Carbon Fiber.. TItanium.. Aluminum..steel they all ride slightly different. If you want the fun of building it yourself and get a propper fit go to your LBS and get fitted properly decide on teh frame and group you want, buying all at same time should get you a discount.. As for groups you have two options.. Campagnolo and Shimano.. WIth what you are looking at spending you could go fairly highend on the components depending on what frame you choose.

For commuting, a pure road racer has some limitations. A sport/touring bike will have more clearance to fit wider tyres and fenders, for wet weather riding, and will have an attatchment point for a luggage rack. You wont be able to carry a full touring load on this style of bike, but a properly fitting rack will take commuting loads with ease.
Racers would have to fit a seatpost mounted rack, which is less stable, much heavier, and rated for a smaller load.
Check out maybe a Bianchi San Remo or a Jamis Aurora.
Regarding clearance, you have to see what kind of brakes they use. Racing calipers have little clearance. Cantelever brakes have loads of clearance. My bike uses light-touring calipers with medium clearance, and for this kind of riding, are my favourite.