My baby brother is getting married! We're so excited! They don't have a lot of money so they've asked my sister and me to take pictures at the wedding.

actually, i'm not too worried. it's going to be a very small wedding, just the siblings and parents, so about 16 people at a small chapel.
http://www.pilgrimchapel.org
I suggested he might want to rent us a lens to get better pics during the ceremony. I anticipate that the light will be pretty low. Do you think this is necessary? I have a Nikon D80. I thought my 1.8 50 mm might be a good choice to use but wondered if I should also try to get a faster telephoto like a 2.8 200mm or something. Any ideas or suggestions?
My sister has the D40, so she can only use lenses with the autofocus in them. I also have a 90mm 2.8 Macro which I thought might be nice for ring shots, etc.