We do video production as part of our company's business, and we're exclusively Apple here - audio production as well, which (with proper external hardware) is very similar to live audio production. But I know that people use software like Ableton on PCs for work like that too.

If she's using a DAW like Logic Pro or Ableton the laptop will need to be beefy so she doesn't get the dreaded system overload alerts, unless she bounces individual tracks inline, but even then you want enough cores and memory to do all of the effects and mixing in realtime.