Cool, we were there that time in '06 too. Agreed that the crowds were very light. As an example, I rode Tower of Terror with zero waiting twice; the second time there were only 4 or 5 others in the elevator with me (surprisingly not as much fun...alot of the fun is hearing everyone scream!). Mission Space was about a 5 minute wait. Soarin was new so it was about 70 minutes. Big Thunder had about 50 minute waits but only because Splash Mountain was closed. Which leads me to another point: as I'm sure you're aware, prepare for one or 2 or 3 or 4 major attractions to be closed during your stay. For us it was Splash, Buzz, Test Track (aka Fast Track, FastPass, etc.) and the Riverboat.
Weather is iffy, but I love cool weather. It didn't rain a single day for the 9 days we were in Orlando this year (1/21 - 1/30). Highs were in the high 60's to low 80's and sunny. I would call it PERFECT weather.
I will be there the week before you in '07, God willing, since our Annual Passes will expire the week you're there!