I have 5 computers to hook up to my home network, one by Ethernet and the others wireless. If I hook up the older computer to the Ethernet cabel on the router it seems to slow the wireless signal down from the router to the other computers. What could cause this I have a Belkin wireless G Plus Router. The older computer is a Mac G-4 450 dual with OS X

This is indeed strange. It shouldn't do that. But, you never know. It could be that the Mac is downloading a large patch/update from apple OR the NIC is faulty on the Mac and is causing a broadcast storm. See what the Mac is seeing on the network and take it from there. First close all programs (browsers, apps, etc) to make sure that nothing is using the network. Start a Terminal session and switch user to root. If you've never done this before then do this from the terminal window:



$sudo - sh (you'll be asked for your current user password)
# tcpdump -n -i en0

This will dump any/all traffic that your mac is seeing (sending/receiving). If you're not expecting it to be sending or receiving anything then you should only see the occasional arp. If you can't see the screen because it is scrolling too quick then you may have found your answer.

Lets start there.

Casey