How to go about reinstalling windows and getting itunes back to how it was.

[.:SAmSuNG:.]

Basically i have a new pc for my sister coming this week that I will use her old drives from her current pc in the new one. Now this will be formatted when i re-install windows7.

My question is how do i back up all the iTunes library so i can easily get it all working again after i have re-installed iTunes?

Thanks.

 

[.:SAmSuNG:.]

Thanks!