The 24-70 f2.8L

snoboarder has very accurately described it so far.

I can only add that I too enjoy the feel and size used on my Canon 30D.
I just attended a snowmobile show in Mpls Mn, and this format worked perfect.

I have to admit the kit lens 18-55 gets you started, but in reality I may donate it for a worthy cause.

The L series lenses by Canon are Pro series.
Once you take the step, Your hooked.

Here's a bit of advice.
The L series lenses hold their value regardless of age.
Going to auction sites to find used ones will prove my point.
You'll find your bid within 300 of new price and yet the lens is already
2 years old. No warranty, may have hidden problems, or maybe perfect.
The lens I was bidding on retails for $4000.00. A 300 f2.8L IS.

The best way is new.
Your investing in a perfected time machine.