I have been to Disney World in February where it was in the 70's and just absolutely beautiful...and I have also been in February when the weather was rainy and cold...You just never know...We already have our flights (10 of us) for next February...so..I guess we will be ready for any kind of weather!
Crowrds are light except for President's Day weekend and into the middle of that week.
As Disney's Daughter said above, the weather is unpredictable. When we were there in Feb 2004 it was in the 30s a few mornings but later in the week it got into the 80s during the day.
We went in Feb '03 and '05... had magnificent weather both times. One morning, it was a bit chilly.... about mid-40s, but by noon I had my jacket off. Feb is one of the lowest rainfall months in Orlando, as proven here..... http://weather.yahoo.com/climo/USFL0372_f.html
I'll also caution you to avoid Presidents Day and the 3-4 days before and after it. We were there the week prior to Pres Day this year and noticed significantly larger crowds on Thu, Fri, Sat. Still nowhere near summer levels, but not uncrowded by any means.