I'm using 2003 as a print server. I like the way it reports problems like out of paper to the client.
Back when I was using a unix based server, no such messages were reported. It used a virtual printer and then transfered the job over to the actual printer. It didn't forward messages back to the client (since the print job always goes through immediately to the virtual printer).
Maybe there is a better way to setup a unix print server...You will probably need a postscript printer for proper unix support though (ie avoid ghostscript).