Canon EF system lenses will fit both the film and digital cameras, so if you already have a set for your Canon film camera they will be okay with a Canon digital slr. All the autofocus and autoexposure facilities will work as on the film camera.
This is the case with all major manufacturers, Nikon, Olympus, Pentax etc. They do this so that when (if) you change to digital you will buy another camera of the same make as you do not have to buy a new set of lenses.
The only difference when using the lenses on, for example, a Canon digital slr is that the digital sensor is smaller than a 35mm film frame. This means that the focal length of any lens is increased. In the case of Canon (excluding the new 5D which has a 'full frame' sensor) this difference is a multiplier of 1.6x. Therefore with a 100mm lens, on a digital camera it is the equivalent of a 160mm lens. My 500mm lens is the equivalent of an 800mm lens. Great for telephoto but not so good for wideangle. A 28mm lens becomes a 44mm lens. so you get less of a wideangle. To overcome this you can use something like a 20mm which gives you a 32mm.
You can now buy lenses especially made for digital that are built to compensate for this difference. However it is not a problem at all, you just need to get used to the difference.
Another good website for camera reviews is :Steve's Digicams
Thanks for the compliments all.