So I am buying a new lens...?

I'm getting the Canon 7D very soon, and I really want a new lens too. Should I get the Tamron 17-50mm or the Sigma 10-22mm? Here's an inventory of the lenses I have: 18-55mm, 28-135mm, and a 50mm. I was kind of leaning toward the 10-22mm, since I don't have a wide angle lens yet, but the f/2.8 sounds a lot sweeter from the Tamron lens vs the f/3.5-5.6 from the 18-55mm I currently have. I wish I had the money to get both right now, but eventually I will. I just need help picking the one I should get first! I'm a very indecisive person. Thanks for all of your help. :)