Some computers have a recovery partition, but usually in order to use them you need a recovery CD that comes with the computer - Did she get any kind of recovery disc? There isn't anything analogous to that in Windows, but there are system restore points. These will simply restore the computer to the state it was in when a particular restore point was made. I don't know if she would have any restore points that suit though. I turn them off because they take up too much disk space.

Does she know the XP CD key that was used with her current installation? Because you may decide that there's no moral issue with downloading an XP image for use with an existing key, since the key is what you pay for. I mean, Adobe tech support actually advised a friend of mine to download a pirated version of Photoshop CS3 because the installer on his disc was bugged.