I have a daughter and she stays with me 1/2 the year. I have joint custody of her with her mother. Her mother claims her every year and I told her I would be claiming her this year since as of September 2008 I have had her permanently. Am I able to claim her? I was told that I can because I make more gross income then her mother, which I always have, I just never did anything about it. Please let me know.

The parent whom the child lives with the most time during the year is entitled to claim the child, and if the child lived with both parents for the same amount of time then the person with the higher adjusted gross income gets to claim the child. This is unless there's something in your divorce decree that specifies otherwise. Read pub 501, pages 13 & 14:

http://www.irs.gov/pub/irs-pdf/p501.pdf