Bike Shopping

First, a quick update: Since you last heard from me, I've been pretty much limited to Tuesday/ Thursday Hill rides and Saturday Tempo Rides. Yes,  I've missed a couple of rides because I got home late from errands. Yes, I've tried out mountain biking a few times as well, but decided its not for me. Yes, I did retrace the Simi ride a few Sundays ago.

Now, on to todays Topic: I'm shopping around for a newer bicycle. Why buy a new bike? Well, my Nishiki has problems.

First and foremost, the frame is too large for me, and weighs about twice as much as most bikes made in the last 10 years. It is like riding a tank.

Secondly, the important components- drivetrain and brakes- are not as reliable as I want them to be. I've tried to jerry rig a better drivetrain, but I frequently find the bike shifting through gears or stopping between gears. The result is it's not fun trying to get the tank up a hill. For the brakes, they work, but they aren't as responsive as I'd like. Naturally, that is not much fun when going down a hill either.

So, a new bike is in order. Now, what should I get?

A local bike shop is selling an '08 Specialized Tarmac Expert for ~$2400.
A person I met riding is selling a Trek 5500.
Finally, someone I've met once is supposedly selling a bike, but I'm not sure which kind or how much he wants for it.

Either way, I'm hoping to get one soon. Suggestions or opinions are welcome.