Several companies offer a card reader attachment for your computer for various types of memory cards. It may take a little research on the internet on you part, but they're out there. Prices aren't all that expensive, either.
memory card, like SD or Memory Stick
You shouldn't need any hardware, but often time the software comes with the camera and if not you can go to the Camera's Manufactures website and download it. Also most the time you just have to plug the USB into the camera and the computer and it works right away without any software.
A digital camera does not put Any "Device" into a computer. A digital camera acts as a storage device and an output device, it transfers jpeg and other similar files to computers as well as mp4 and other movie files.
Input When connected to a computer the camera inputs images
An input device
It is an input device because you are inputting pictures from the camera to the computer. It could also be considered an output device since it can display the pictures on its LCD display.
Input as it sends the video/images into the computer.
A digital camera is an input device because it captures information and stores it on the device via the memory card(which is a storage device).
Input
A webcam is a motion capture device that transmits a digital signal to your computer, usually via USB. A security camera is usually sends an analog signal to a VCR or other analog monitoring or recording device. A webcam can be used as a security camera with little difficulty, but an analog camera cannot be used as a webcam without major modifications.
Device Driver
Depending on your camera it may be a SD card or a CompactFlash card. If you are saving from your computer any storage device that can be connected to the computer will do.