Is it straight forward to have a linux machine access the data held on a PC running Windows?

I’m thinking of buying my partner a Netbook, all she wants it for is to access the internet, check her email and facebook etc but she would also like to transfer a few movies from our home PC occasionally to watch when she is out and about.

Can I set it so she can access our home PC and copy files to her Netbook via our wireless router when one is on Windows and the other is Linux?