Lets give it the benefit of doubt I will answer your initial question.
First you have a 40D nice camera and it can do the job.
As someone mention before you did not present a flash on your equipment trust me you will need one and to that, add a diffuser, I will suggest the Gary Fong is big and ugly but do the job.
What about Memory cards how you are running with those you will need at least 4 with 4gb I mention that because do to your inexperience you will need to shoot a lot more in order to nail more photos.
Now I will put a real situation that happen to me once. I was using my D300 and I was doing a photoshoot for a model agency sudendly one of my big CF card 8GB get damage and I never was able to recover those photos we have to reschedule the shooting for another day thanks GOD that we can reschedule on a wedding you can not do that and that would be a sue for you and trust me you do not want that.
Now how you are going to prevent all those things?
Beside that get the flash that you need 580exII cost around $450, the flash only cost more than the total that you are going to receive for the wedding. Now, you are from NYC so you can rent it on
adorama fine those are 35.
Another situation if your body get broke what you are going to do?
If somebody drop a glass of wine or liquor on the camera that you plan to buy and return the store do not want that back.
My point is that if you are really interested on doing wedding get yourself the 5dmkII or you can get a 7d and make the investment and continue to looking for more geeks to get the money back and next time do not charge so cheap because now you know why the pros charge a lot not only for the image quality if not for the investment that they are carrying on their necks to get those nice photos.