drkshadow03 is correct. "A little" has a positive connotation and "little" has a negative connotation. Let me give you another example: (+) a few - I have a few apples, would you like some? (I have enough to share.) (-) few . I have few apples, only enough for myself. (I don't have enough to share.)

She has little sugar would tell me she has very little and I shouldn't ask to borrow any because she probably doesn't have enough for herself. She has a little sugar is more positive. It tells me she has a bit stored up for himself as a comfort and that I might be able to ask for some. It might be easier to see the difference with a different example. He has little skill in chess (he's not very good at chess) He has a little skill in chess (he's good at chess. The best? No, but still decent.) Adding that one little "a" can give the sentences opposite meanings.