Be aware that to see shared music on your subnet in iTunes 5.0, you must choose 'Show Radio' in your preferences. Strange, but true. I tested this on all of the Macs in our office this morning. They can share to and from v4.7 to 4.9, but v5.0 users cannot see shares until they turn on the radio.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050907204349122