I would give a Dell Mini 9 or 10v a very close consideration. I have been using a Mini 9 now for almost 3 months. I have been impressed with just how well it works with OS X. I am a devoted Mac user who has been without a functioning portable for over 4 years before getting my Mini.
It will install MS Office, iLife and iWork and run all of those titles reasonably well. I go online and do everything I need or would want to do. I haven't tried any processor intensive programs because of the limited main drive space and the fact that the Atom CPU is only a single core processor. Although these limitations might make it sticky for you to seriously consider a mini, it would most likely be more than adequate for your 7 year old daughter. In fact, I am seriously considering purchasing a Mini 10v for me and passing my Mini 9 down to my 11 year old who is entering middle school (6th grade) this fall.
I would trust it for his needs and I am not just an uber Mac geek, but I am also a computer and network technician who is well-versed in operating, setting up and maintaining just about every OS currently in use. Having tried a Mini 9 with Linux and Windows XP, I can tell you that not only does OS X on my Mini provide the best possible overall user experience, it runs considerable faster as a Mac than another platform PC.
Check out eBay and the clearance section at the Dell website. The Mini 9 has just been discontinued and the 10v has the same chipset so not only will Dell become highly motivated to clear out its refurb Mini 9s, but many OS X users may be wanting to upgrade to the 10v, especially considering that it comes with HD video support.