Personally I don't think that 5th grade is appropriate to have her own laptop, especially a 9 yr old going nto 5th grade. For project and such they should have plenty of computer time at school to complete them. If not, I would let her use a desktop computer at home under strict supervision. 9 yrs old I think is too early for them to be able to have the privacy of a laptop or notebook. You won't know if she is emailing friends, in chat rooms, or giving out too much information to a predator (she may loose socialization skills if allowed to participate in chat rooms/email/IM). I have 1 in high school, 1 in middle school and 1 in elementary school, all three somewhere on the AI spectrum. They have a desktop that does not connect to the internet to use for homework/games and are allowed to use mine to look up internet stuff only if I am watching. (I have caught my older two several times on inappropriate sites. If you concentrate more on what your son is exposed to your daughter will take advantage of it.) The older two are the only ones that have used it for homework so far and at that not until 7th grade. In 5th grade stuff still needs to be handwritten to put emphasis on fine tuning fine motor skills, too. It also helps the information to "sink in" allowing children to learn the subject matter better. Personally I think you will do her an injustice by getting her one so soon. She will become dependant on it and not learn how to do things by hand (there is some sort of calculator on any computer, spell check, etc.). My 8th grader will be taking required computer classes this year to learn how to properly utilize the computer programs. I would encourage her to enjoy being a kid some more.
All I'm trying to say is weigh the pros and cons a bit more before jumping in to get her one. Once she has it you can't go back. She isn't even old enough to babysit yet. (I do believe 13 is the youngest by state standards.)Please, for her safety, think it over.