Scott makes some good points. Please keep in mind that a wedding is an important event, and one is often literally a "once in a lifetime" event for many people. It's not something that can easily be re-created.
Speaking of lawsuits, PPA offers insurance for just that sort of thing, and yes, people DO sue photographers when the wedding pictures aren't what they expected. Not just the "Oops, my camera broke" but even just "I don't like these..."
If this is your first wedding, please be honest with both yourself and the couple, especially the bride, about your skills. Make sure she is comfortable with the situation. Presumably your fee reflects this, which should give them a clue, but honesty before the shoot can prevent problems afterwards.
A few years ago I shot a wedding for a friend. When she asked if I'd shoot it, at first I simply said no. She thought it was about payment and said "I'll pay you for it!" to which I replied, "It's not about the money! I'm not a wedding shooter, and not qualified..." She persisted, and I agreed to shoot it with one condition. I insisted that she have somebody else shoot it as well.
I did this for two reasons:
1) I wanted a backup, in case I had equipment problems or just plain didn't get good shots due to inexperience.
2) It's good practice to have a second shooter at a wedding, since sometimes you're not in position to get a critical shot. With a second shooter, he/she would be in a different location, and hopefully get the shot you can't.
Another factor that helped was that this was her second marriage. The wedding was nice, but not the big huge formal affair that some are. She didn't want the "story book" images some brides do, and was OK with a "photojournalist" approach to the shots. (I did try and do some creative shots as well though.)
We ended up having 3 shooters. Myself, her sister and another relative. The sister did pretty well, and my shots met her expectations. The 3rd shooter had problems and didn't have anything useful at the end of the day.
I don't know if you can find somebody to shoot with you or not. If you can, it might be a good idea. A second shooter means you have backup gear (theirs) another angle, and often a different approach to shots.