Which IS Lens for Digital Rebel XT?

[ChesapeakeTechie]

I've had my Digital Rebel XT for about a year and a half, and am now looking at upgrading to an IS lens from the standard lens. Big question is, which one??
I've been reading that the 17-85 EF-S lens is a great all purpose lens. I've also been seeing great photos and reviews on the EF 28-135 IS lens which I believe is a bit more telephoto?
Is one lens faster than the other? This will be my first additional lens...

Thanks!!!

 

[boBQuincy]

To muddy the waters even further, if you don't mind the price, is Canon's 24-105. This is L glass, with a constant aperture across the zoom range. The wide end is not as wide as I would like but otherwise the lens is really good.

 

[fitzperry]

I take it you probably have an 18-55 kit lens? I'm a Nikon gal so I don't have experience with those particular lenses, but I tend to use the wide angle a lot and wouldn't want my widest to be 28mm. Then again, if you don't shoot at the wide end much and are keeping the kit lens so you'd have it if you need it, you might enjoy the range of the 28-135.