Trek makes 3 series of bikes that begin in the 2k range and go up - the Pilot, 5000, and Madone series.

I'm in the same boat as you. 2005 Trek 1000 w/Sora 8 speed drive train (except Tiagra rear) and am looking to upgrade to all carbon. If you're on a budget, I test drove the SuperGo Scattante CFR and was impressed at what you get for $1,700.