Okay, I'll admit, I did not read all of the posts above.

I have had an aluminum frame that was a little too large, and now ride a carbon fibre bike that fits me correctly. The first bike length on my carbon fibre bike, on our rough paved road, and I was in love. If I had bought it sooner, I would have ridden it so much more over the years.

I just saw that a fellow TEer has a carbon bike for sale, that looks like good spec and good geometry for a newbie like you. It's a good price, (1/3 what I paid for mine), and might be in your price range.
http://forums.teamestrogen.com/showthread.php?t=22830

Absolutely most important is that the bike fit you. You'll love carbon fibre, but stick with your budget and buy what feels best. I totally agree with that. And don't forget, with your budget, you'll need to spend on helmet, shoes, gloves, and clothing. Look for deals where you can, and try lots of stuff on.

When it comes to shifting, learning the pedals, biking strategy, motivation, come on back - these ladies are awesome!

Hugs and butterflies,
~T~