I'm going to be the first one to jump into the snake pit lol
First off let me say that everyone has to start some where...period. Whether it's with weddings, portrait, cars...whatever. But usually that person who decides that they are going to shoot weddings has either assisted a wedding or at least shot portraits.
I don't care who you are but you can't shoot a wedding with an xsi a kit lens. Well you can, but we know what the results will be. Most churchs don't allow flash, so therefore, most photos will only result in high noise due to high ISO. Also you are limited to ISO since most pro-sumer cameras only go up to 1600, some at 3600 just depending on what you have.
This isn't targeted at you since obviously I missed something after I made my initial comment but this is just as an "in general" comment. Michael made an awesome offer and it sucks that she didn't take it. I think she will enjoy her photos a lot more having someone that is a wedding photographer.
Who the hell knows, you could of gone in there and done an awesome job and found your calling...hard to say but as a bride (once and never again) you only get one shot at getting those pictures. There's no repeat of that day so having Uncle Bob with a camera shoot my wedding, wouldn't of even been an option.