I believe that a Canon FD lens will not come to infinity focus on a Canon EOS without an adapter that includes a correcting lens [these correcting lenses are (apparently) of very low optical quality in most cases]. This is because EOS lenses have a backfocus of 44mm, whereas FD lenses only have a backfocus of 42mm. in otherwords, the FD lens is effectively too close to the camera sensor, preventing infinity focus.
Lenses which have a backfocus > 44mm can be used on an EOS camera, although you need to take the backfocus of any adapter into consideration as well. Manual focus Nikkor lenses can be used with a Canon EOS camera (I have several NIkkor lenses which I have used with my Canons); Pentax-K, Contax, Leica are also options. See here for a list of different lens mounts and their associated backfocus:
http://en.wikipedia.org/wiki/Lens_mount