Wedding photography involves a lot of portraits and  group portraits indoor under low light.  The full frame digital SLRs have the advantages of  higher image quality and wider angle of view.  Canon 5D Mark II is a great canon DSLR for wedding photography.  Although Nikon lenses are more expensive than Canon lenses most of the time, Nikon lenses are of better optical quality.  If you prefer Nikon, Nikon D700 is the one for wedding photography.

The best Nikon lenses for wedding photography were discussed previously:

Nikon 14mm – 24mm f/2.8G ED-IF AF-S 

Nikon 24-70mm f/2.8G ED AF-S , buy from amazon $1999.95

Nikon 70-200mm f/2.8G ED-IF AF-S VR Zoom Nikkor Lens, buy from amazon $1899.95

In addition, you definitely need a back up camera just in case D700 is out of order.  Nikon D300, or even Nikon D90 will be  good back up cameras.

Related posts:

1. Best Nikon wedding lenses
2. Best Canon digital SLR for wedding photography-Canon 5D mark II and lenses
3. Best Nikon digital SLR for sports photography