Yes, your "old" autofocus EOS lenses will fit a new Canon digital SLR. However, note that on most Canon digital cameras, there's a 1.6x mulitiplier of the focal length, which changes your field of view (e.g., your 50mm lens becomes 50mm x 1.6= 80mm field of view)

It's the old Canon FD manual focus mount that is incompatible with the Canon EOS cameras.