My 2nd lens I got, not counting the kit lens, was the 10-22 (the first was the 50mm). It's r-e-a-l-l-y w-i-d-e and I'm totally glad I got it. Comes in handy all the time. That usually lives on the camera and I have the 50mm in my pocket.
Like you, I was boucing between deciding getting the 10-22 or the 17-40L. I decided to go with the 10-22 because I'm on a crop sensor. A friend of mine just picked up the 17-40L last week but I have yet to see his images. The benefit of the 17-40L is that its not ALL wide so its a tad more versatile. ...and to be honest, I was kinda afraid of getting an "L" lens and not want to settle for any other glass after that. Don't get me wrong, though. I had a hell of a time trying to decide. You probably wont be unhappy with either lens.
I also picked up a 75-300mm (old model, non-USM/IS) on Craigslist for $100. The worst piece of glass in my kit but I wanted a cheap telephoto lens to round out the collection until I can afford a decent lens. I figure this was cheap enough to fill my needs until then.
Oh, if youre looking for a bag to carry all your gear in, check Amazon. They have a very decent camera backpack from Canon for only $36.97 (free shipping!). "Canon Deluxe Photo Backpack 200EG for Canon EOS SLR Cameras (Black with Greenish Accent)" is what you want to look for. Search for "B00009R6TA". I just got one on Monday. The gf liked it so much, she wanted one for herself. That one is on it's way.