I posted this somewhere else but can't find it right now. I used to work in a shop and fit a lot if people for a board, boots, and bindings. Here is what I suggested all the time and it used to help a lot.
1) buy boots first and take your time picking them out. This is the single most important piece of equipment you need since you have to wear them for eight to ten hours sometimes. Go to a shop and try on as many pairs as you can from different companies too. Just because one boot fit one way don't assume another will fit similar. Go for a mid range boot, not too stiff but not overly soft either. Let your feet decide which is the best and don't stress about dropping extra scratch here, it's well worth it later.
2) next pick out bindings that fit your boots very well. A good rule of thumb is if you buy burton boots burton bindings will fit them best. But other will fit just as well too. But make sure it a good fit and again you can spend here because you can recycle them later to another board. Get a mid flex binding again not too stiff but not too soft used for park either. A good set of bindings could end up on three or four boards over their lifetime.
3) finally pick your board with the remaining money you have. This is the most disposable of your equipment because its the only one that comes in contact to with the snow, rocks, dirt, and other boards and skis. So you will replace this sooner. So make sure you buy something in your weight range first time out and maybe slightly longer too. This will let you ride pow, and give you good stability as you learn. You can size down later once you get better and figure out where you want your skills to progress.
Now I know I'm going to catch shit for this but I would steer clear of Burton EST boards for now. They are expensive, and you will have to buy EST bindings that will only work with a Channel Board. I say this so later if you decide you want to try out one if the many other board companies out there you can use your current bindings to do so. You can always buy adapter plates to put them on an EST board but an EST binding can only use a channel board. This way you leave your options open.
Good luck buying and pick wisely, listen to the shop employees advice and you should be able to get hooked up with good setup that will keep you going for a few seasons.