Hey Gregg,
Forgive me but I dont know much about your background, goals, or current situation... but I went digital at the beginning of the year, and am just getting started in the business, so I think I can relate a little bit.
1st of all, there's a LOT more to digital than just the camera body, I'm sure you know this, but if you dont really budget for all the little extras, you'll be stuck. You're going to need a good computer with lots of storage, CF cards, a backup body, probably a few lenses, flash etc, etc... it ads up FAST. The camera body is only one small peice of the puzzle.
Personally I've always used canon, and I am a big fan.. however, if making the switch means you have to get all new lenses and flashes, it's really going to blow your budget. Contrary to popular belief, Nikons DO take pictures

. I have used a D70 at a wedding, I have proof
If shooting weddings is your goal, what you want is a cabable SYSTEM that you can rely on and get to know and use well. You want this system to work for you as soon as possible. Once it works for you then you can start getting gigs that pay for new equipment. I'm assuming you already have some Nikon film cameras with lenses that will cross over.
This is what I'd do if I were in your situation (which I dont know much about, so I may be way off)...
Step One: Get started right NOW using my film cameras. I went digital because I thought I had to to compete in the industry.. I also thout it would save me money on film costs and would provide an easier workflow.... this is all partially true. What I didnt factor in was the huge cost of all the support equipment, software, etc that is necessary to make it happen. I also didnt consider that while I like the digital workflow better, it is WAY more time consuming and has a pretty big learning curve.
Step Two: Earn enough to buy a dSLR. If you are SURE you want to make the switch to Canon (which IMO is eventually a very good move), I'd evaluate my budget. If it's a stretch to get 1 body, I'd start out with a nikon dSLR. Something like the d50. Dont invest heavily in other nikon gear.. just get the camera, use the lenses you already have, and get to learn the workflow. Shoot it alongside your film cameras. You dont have to go digital all at once.
If you've earned enough to buy 2 bodies and some lenses, then sell your nikon stuff, and make the switch (this can be EXPENSIVE).
Again sorry I dont know much about you situation.. I just remember when I was trying to get started about 10 months ago I really thought I HAD to go digital. I was really happy with my film camera, but everyone in the industry seemed to be digital (not true). So for me it was between filling out my film camera gear (which would have eventually translated well to digital since I've always shot canon), or go digital. Now I have a 20D, a flash, and some nice glass (bye bye tax return, lol), but I have to use my film cameras as backup or borrow 20D's from friends when I shoot weddings. I'm still 50/50 about the desision I made. On one hand it is REALLY nice to not have to worry about film and developing costs (esp. for someone like me on a tight budget), but at the same time I love film (the look, and the feeling I get when making each exposure). The techie geek in me loves digi but the artist and the family guy miss film just a little bit.
So... this is probably more than .02 worth but I've been through something similar.. maybe you'll glean something helpful out of my experience and random thoughts. If you have any questions, feel free to ask...
why do you have to shoot digital at your brothers wedding?