95%+ comes from you - the photographer. The equipment you use can make it easier and faster for you, but in and of itself it will not make "the difference" between good and bad shots.
Any camera can take great shots if the objects are "posing" - i.e. arranged shots. As I think Thomas mentioned, the lighting becomes paramount. Lighting can come from existing non-camera sources and be assisted by your equipment, flashes, screens/reflectors and whatnot.
The more challenging part of wedding photography are the shots that capture the "feel" of the wedding - i.e. those shots that are taken without any posing. The bride's eyes when her father is speaking, the grooms face as he sees his bride for the first time, the children running around, laughing faces as the brother fires off some raunchy jokes, Uncle Bill's inebriated smile as he raises his glass in a toast. The focus of the bridesmaids as they dive for the thrown bouquet of flowers.
From your post, it seems that you are not a veteran in wedding photography, but your dedication to saving for equipment suggests that you will go to great lengths to get some great pictures.
My personal advice - such as it is - is to get something sooner (i.e. save for a shorter period of time) and start practicing composition and shooting people. Get a camera quick and start taking shots at every single party you can get to. That practice will have a much higher impact on the quality of your photos than any equipment will.
Grab the Nikon D80 with the very versatile and reasonably fast 18-200mm VR lens and a flash or two and you'll have more than enough to create world-class wedding photos. Or, grab a Canon equivalent. It matters very little, compared to practicing and composition.
Most importantly, get out there asap and shoot people in similar settings - play with the lighting, different diffusers on your flash(es) see what works with the kind of pictures you want to get. Visualize the great moments in a wedding - and there are many - and try to grab as many of them as you can.
Whatever you choose to do, I wish you the best of luck. Giving the gift of great photos from a wedding is something to be very proud of - of they're good