I know exactly how you feel. I've had a Trek 2100 for two seasons and I love "Nathan" but I definitely have new bike envy.

I made the mistake of demoing a Madone for one of the days of my week long trip. There was a very noticeable difference on a eighty mile ride on an all carbon fiber bike. The components were much smoother as well.

I keep telling myself that I haven't earned a new bike yet.....but that hasn't stopped me from wanting it. I try to remind myself of all the more responsible things I could be spending that money on instead, but I still keep dreaming of that sweet, sweet, new ride. I have a picture of my Project One creation above my desk at work. Perhaps someday I won't be able to control myself and I'll order "Nathan II".