Mac-Linux filetransfer

["DSC@Siltec" <dscpubl@siltec.lt>]

Okay, here's my problem:  

My PC apparently can write CDs okay. 
My Macs, more and more, cannot.  Technically, they come back with
"medium error".  
Some of it may have to do with disk fragmentation, but that's a problem
with my 
Macs.

I'd like to do two things:  
(1) start backing up to the PC (Woody),
(2) write my CDs from the PC.

My Mac and my PC both have ethernet, and I am aware that an ethernet
cable
can be made with a couple pairs reversed to run directly from one to the
other.

However, that still leaves the question:  how do I set up file transfer 
between a Mac and a Linux PC?