These boards are a great starting point and there are several other discussion boards on the same subject matter.

Please do research and be aware that all vinyl windows do not look or perform like most of the junk you will find at Home Depot, lowes, and other supply stores.
There are high performance vinyl windows that look very nice and perform much better than a wood window .
Higher end vinyl Brands would be:
Okna , HiMark, Soft Lite, Sunrise, Gorell, Starmark

Hmm... I thought I replied but I don't see it up...

Anyway, thanks to both of you. I did find this primer: http://windows.lbl.gov/pub/selectingwindows/window.pdf (posting it here in case anyone else comes across this thread looking for help).

I did contact Okna b/c I saw a lot of recommendations for them on this board, but they don't sell in California.

One question after reading that primer. How important is the u-factor and solar gain/loss in a moderate climate? I live near San Francisco, and our weather is in the 40s-50s in the winter and 70s-80s in the summer. But we do have on one of our floors, one wall that's almost completely all windows facing west.

Thanks! And I'm sure I'll have more questions after we meet with a salesman.