| | Re: What lens for Canon?
I never used the 18-55 that came with my camera (XTi - 400D)
I bought the 24-105 lens, including the IS feature, and it's a pretty good all-around lens. Cost maybe around $1000 new.
If you eventually invest in a more expensive lens, I'd strongly suggest buying some sort of filter, as well. I chose the UV filter. For $20-50, it's a worthwhile investment, to protect your lens. Even if you don't feel comfortable to use it as protection, consider it a dust-guard. It screws on to the lens, so it minimizes the dust getting into the lens area.
Once, I accidentally dropped my camera, lens down, while the lens cap was still on it. Well, the UV filter completely broke, but there was not a single dent/scratch on my lens! The camera was in a semi-cushioned bag when I dropped it, but whew!
And yes, it still works very good!