Im trying to use the airport to connect my imac to the existing pc internet. I have the AT&T wireless and Ethernet system but im not sure how to get my mac upstairs onto the internet. ive slected my network in the airport but i try to go into the internet and it says no connection for internet. then i go to network dignostics and it tells me nothing. someone please help!
Try turning off wireless security in the router temporarily (see literature which came with it or download manual from maker's site for how).
Most issues with Mac relate to wireless security, often just as simple as Apple using non-standard terminology to describe security standards. But on some models I've ended up having to use 128bit WEP which needs ridiculously long HEX passphrases.
Hhmm.. weird. Check your location settings to be sure that you have a wireless location setup. What you could even do, delete the auto setting, and set up a new location that ONLY uses the airport. Then attempt to connect. I was actually Mac certified until a couple of months ago, lol. I kind of suspect however that maybe with the iMacs having a lot of aluminum also may not get as a good of a connection on wireless..maybe the aluminum interfering or something....What type of security are you using? I'm using WPA on my home network and have no problems on my MacBook from work.
Btw, how old of an iMac are we talking about? Old candy colored iMac or a newer one?