What type of files do you want to see? All major graphics formats are platform agnostic. MS office apps are cross platform. There should be just about zero docs that yu can't open on a pc as ong as you have the right program.
Pre OSX macs did not put an extension, like .doc, when saving. That was teh big problem in opening docs on Windows machines. Now most apps put the extension on save (some have the option, but it's not a good idea to leave it off.
Using OSX 10.3.9 on a G4