My son started crawling at 7 1/2 ~ 8 months and started walking at 11 months. He's 12 months now and walks pretty well on his own (though he does still fall a bit, he can stand back up with out pulling up on stuff).
#1 started crawling around 7 1/2 months but didn't start to walk until she was 14 months.
#2 started crawling on his belly at 5 months and on his knees at 6 months. He was walking at 10 months.
#3 started crawling around 8 months and started walking a couple days after her 1st birthday.
#4 started crawling just before she turned 7 months and started walking a week before she turned 1.