whats the deal with 50s becoming 75 btw? is it older lense on digi bodies that cause that?
Canon have used three different sensors/crop: full frame, 1.3x and 1.6x.
Multiply the focal length by the crop and you'll get the new effective focal length, so for a 50mm lens on a full frame, the lens is still 50mm.
50mm X 1.3(crop) = 65mm
50mm X 1.6(crop) = 80mm
I almost only use a 28mm, have got a 50mm too but I always find the 28mm is faster to focus and gives a nice level of distortion, the colours are generally quite good too.