some more info required really. what do you want to shoot? and IIRC the 400D is 1.6 crop the 50D is 1.3 crop, which may affect your lens choice![]()
The 50d is still 1.6, same as the xxxd's. It's only the 1d series with a 1.3 crop factor.![]()
shows how long it is since i had the 400D 
shows how long it is since i had the 400D
the 100mm macro you mention (from what i've heard) is pretty good as is the 60mm.
17-40mm L is superb, i've used it a lot in a studio and love it. I think it's also good for landscapes![]()

Ok, anygood recommendations then for a wide angle lens upto about £400 suitable for a cropped body?
Ahhh just noticed the sigma 10-20mm on another thread, is the canon version worth the extra cost? Apologies for all the questions but buying and then regretting is something i'm quite good at.