pc files to Mac G5 via ??

I have a pc that is full of music, video and documents, that I want to get onto the mac... All my computers are on the network, so I want to allow the mac to access the pc, and the pc and laptops to access the mac - how do I do this??

I can't figure out how to access the network with the mac, and though I could see the mac on the network from the pc it vanished after I tried to access it.

How to connect a Mac to a PC on a local network.

Thank you

There's also these things called portable hard drives and thumb drives. They work great.