The gopro hd can shoot in 1080p (higher quality), and the 960 can't. My friends have the full hd and dont use the 1080p, only the 720 and 960. I have the Gopro 960 and it's great. My advice would be to get the 960 unless you want to get the lcd backpack, or eventually go 3d with it.
"I dont want a girlfriend..."-fishgills
"You want a blowjob dont you?-banana_man