Hello Mike,
Welcome to the sport of wakeboarding.
Some folks might say right off, "man you are a little heavy for wakeboarding".
I say, BS!
My son in law is right at 300 lbs (I'm at 225) and he is one of the most aggressive riders in our posse and is in his third season, so... for starters I congratulate you for jumping into the sport, it's more fun than a barrel of monkeys!
Just keep it simple to start, set realistic goals, one step at a time, don't try to ride beyond your ability and have fun.
Lots of good suggestions here in the discussion forum but don't take everything you hear or see on it as the gospel, including what I say about it. You got to do some research on your own to separate the real deal from the BSers.
For my two cents I would start out with a large beginner/intermediate board.
Some will argue about what you need and give this opinion or that but because of your weight you "probably" need a 147cm wakeboard as a starter.
"Generally speaking" the bigger the board the more lift/surface area you have for deep water starts etc, so don't go small.
Sometimes a bigger board like this can be harder to control on spins inverts etc but I assume you have a long way to go before you start trying those tricks and you are at the very beginning stages of learning the "basic fundamentals" to start out with.
You should look at the wakeworld.com board tool/wizard as well to help you make a decision.
Mike, get a "Catch Free" shape, not a pro-board.
In other words you need a board with rounded tip ends and edges to start with. I can't over emphasize this Mike.
I would get something that has a "mellow" ride and is very forgiving on edge as I mentioned above. I have seen some beginners go out and buy expensive pro boards with radical/abrupt 3-stage rockers, variable edges, and funky/catchy shaped tips that caused them to spend more time face planting than real riding.
Don't fall into that trap when starting out.
There are lots of choices but based on your weight and beginner level, the board I would choose for you if it was up to me would be something similar to the 147cm Liquid Force Rhythm, also know as the "Huckster".
If you are looking for a "Hoss Board", then this has your name written all over it!
We love the Huckster!
You can still find these on eBay and they are just a great first time beginner board!
My very large son in law learned how to wakeboard on it and we use this board to teach many of our new riders with great success.
It is very cool seeing a 300 lb dude getting air and doing surface 360's like a mug on the Huckster!
The LF Rhythm is an older ride but seeing it should give you an idea of what I think you should be looking for in a "shape" for a beginners board, here are a couple links to check:
http://www.wakeworld.com/boardguide/GetReview.asp?ProductID=1076 http://www.wakeworld.com/boardguide/getboard3.asp?ProductID=1391 As you progress you can always buy a more advanced board later and keep the beginner model around as a back up and use it to teach others how to ride when you become the "Shez".
I would also recommend starting out with a continuous rocker or at most a subtle 3-stage. CWB makes one of the best beginner boards ever made called the "Sol" it is rated for your weight but is only a 141cm board
http://www.wakeworld.com/boardguide/getboard7.asp?ProductID=2977. The Sol does not win any prizes in the most pop department but it is easy on deep water starts because it is neutrally buoyant. The Sol is very stable, fun and easy to ride. You can change out the stock fins to smaller P wings or ride it finless for a looser feel as well.
Another very mellow board is the Hyperlite Motive,
http://www.wakeworld.com/boardguide/getboard10.asp?ProductID=4815. The Motive is a great all around board, very forgiving and has a mellow ride, a better first board than the Motive would be hard to find.
Another great beginner board is the LF Omega:
http://www.wakeworld.com/boardguide/getboard8.asp?ProductID=3616 Again you can see the more rounded tips/edges and continuous rocker design in this shape.
The Liquid Force Trip might also be a good choice
http://www.wakeworld.com/boardguide/getboard10.asp?ProductID=4694 it is a little more aggressive than the other two but still somewhat forgiving and very fun to ride.
Something I would not go beginner on, though, is bindings. Spend some jack for some pro model bindings. Your feet need to be comfortable. If you buy cheap bindings expect your feet to hurt, it's that simple. Hurting feet means short rides. Probably one of the most comfortable boots out their is the Ronix 1 boot, although it is not my personal favorite. I prefer the O'Brien Xenon for comfort and flexibility, lots of personal preference in a boot choice. CWB also makes some very comfy bindings and I have heard good things about the faction boot
http://www.wakeworld.com/boots/getboot10.asp?ProductID=4653 . If you go with a high end pro binding you most likely will be satisfied, just don't go cheap here.
Get a "hinged" USCGA life jacket, NOT A non-CGA Vest!. O'Brien has a special on at a few net sites for about 40 bucks. A hinged jacket gives you much more freedom of movement and you don't feel bunched up like you do with most standard life jackets that were not designed specifically for wakeboarding.
Try to get a "no stretch" line and a good handle. I have had cheap handles break in the middle of a ride and that isn't always pretty.
If you can get to a well known/respected pro wake shop you can get the best advice and try before you buy. I have found them to be extremely helpful and this scenario is probably the ideal situation but one is not always near these wakeboard meccas of information. In many cases you can still email them for advice on purchase recommendations etc, just don't jerk their chain, if you know what I mean.
Anyways,..Welcome to the sport, remember, having fun, the love of the ride and hanging out with some of the best people on the water is whats most important.
Be safe, be careful, and share the ride when you can.
aka The Wakeboard Geezer