Single earner; Married; no children; gross take home 77K; currently claiming 0; have been advised I can claim up to 3 given mortgage insurance and medical out of pocket. Looking to increase spendable income without having to owe the government in 2010 for 2009 taxes

Your employer's payroll clerk could probably calculate the exact figure for you. Get that figure, then, assuming your circumstances haven't changed substantially from last year, if your goal is to "break even" at tax time, go back and check your last year's return to see how much your refund was under your current withholding status. Divide that amount by the number of times you get paid a year. That's how much more you want in each paycheck. Have your bookkeeper help you crunch the numbers until you come as close as possible.