Import Photos from iPhone 3GS

Hello! I have an iPhone 3GS mobile. There are more than 1000 photos and videos in all folders including Camera Roll. I want to export all of these photos to my PC, but when I connect iPhone with my laptop. It just shows camera roll folder as its internal memory, it does not remaining 6 folders in my laptop. Please guide me how do I import photos from other folders also or is there any option that I can transfer all photos from other folders to camera roll?
I am waiting for your reply