Need info on Michigan tax law re: online poker gains

[Warteen]

So here's my situation:
Due to recent good fortune, I have moved up rapidly in poker from a point where I was playing for peanuts to a point where I have made (and hopefully will continue to make) real money. For the first time, I will have to declare my hobby income (which has far exceeded other forms of income) to the government here in Michigan.

I have withdrawn around $5k thus far this year, and have (as of this writing, though it is newfound wealth and may decrease or increase quickly) $10k more in my poker account with World Poker Exchange. I keep track of my wins and losses with Excel files, separate for sports betting (new), live gambling, and online gambling.

I'm hoping for some general information (links are okay if they are well-organized sites) on how much I should expect to give back, and the best way to go about doing so. My plan was to file on the $5k I have withdrawn (less the $2k or so I have lost at live gambling), and leave the rest until if and when I withdraw it. I only want to do this if it won't be a problem.
My father is planning to speak with an accountant about my windfall and will probably take care of most of it for me, but I will be the one providing the numbers. I want to be as honest as possible and not do anything that could come back to bite me later. I also want to keep my financial life as simple as possible, if that is an option. Any help is welcome.