Worked for a company 5 years. I recently took a new job, and upon leaving I went into my draw against commission. Is it legal to take my vacation pay I've earned to pay off any or all portion of my draw?? Please help??

Possibly.
http://www.michigan.gov/dleg/0,1607,7-154-27673_32352-41967--,00.html

What if there's no written policy?

If there is no written policy, or if the employer has not set a policy by practice in the past, then they don't have to pay accrued vacation to terminated employees at all. If this is the case, it's much more likely they could do as proposed.

I don't quite understand. I work at a retail store on average of 50 hours per week. Being paid only $300/week draw. I earn 2 weeks paid vacation per anniversary year. There is no law written regarding minimum wage is a must regardless of draw as well being able to take away my earned vacation time upon giving a 2 week notice. I just don't understand how they can legally take my vacation time from what I've earned.

You have a bigger problem then vacation. MI-MW is currently $7.15/hr.
- If you are working 50 hours a week, then under the "normal" overtime rules, you must be paid at least $393.25/week, not $300/week (40x7.15/hr=$286, plus 10x$10.725/hr=$107/25).
- If you being paid under the Retail and Service Establishment exception, then you must be paid at least $357.50 (50x$7.15/hr) now plus an additional commission of at leasat $357.50 when the lookback period occurs.

Unless you are legally Outside Sales (meaning not working in a retail store), getting paid $300/week while working 50 hours per week does not sound legal. The employer can maybe aruge that FLSA (federal law is not applicable), but I am pretty sure that they cannot argue that MI-MW is not applicable. I do not know enough about MI to know if they have an OT rule should FLSA not be applicable, but it is pretty difficult for FLSA to not be applicable.
http://www.dol.gov/esa/regs/compliance/whd/whdfs14.htm

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If you want to chase vacation, knock your self out, but Patty already indicated that MI law does not seem to support you and there is no federal law on vacation.

If however you can make a wage claim for MW/OT violations, you could be talking some pretty serious money.