W-4 Tax changes for 2009?

My divorce was final yesterday. I need to make changes to my W-4. I did get the house and my daughter is living with more 50% of the time. My question, how many exemptions should I claim on the W-4 to avoid paying anything back at the end of the year 2009? If I claim 3 will I have to payback at the end of the year. I know I can use head of household, what else can I use?