According to the specs, that model shipped with 512 MG of RAM in one slot plus an empty second slot. It could be upgraded to 1 GB by adding a RAM module in the second slot or a max of 2 GB if the module that came with it was removed and both slots were filled. Check to see how much RAM is in it.
Definitely check the upgrade advisor, but take the results with a grain of salt. I believe you can theoretically run Win 7 in 1 GB, but it wouldn't leave much in the way of resources to run software and it wouldn't be a very satisfying experience unless her requirements are very modest. If the machine has 2 GB, it's probably adequate (assuming the other hardware meets the Win 7 specs). If it has 512 MG, I wouldn't try to run Win 7 on it...