bought my 24" imac Extreme 22 October...
Received it last Thursday. Was scared to death after reading all the posts about yellow screens, dead pixels, freezing...the list was endless! People returning 2, 3 or 4 iMacs, and still having issues.
Well, I have not had ANY of these issues, not before leopard or after installing Leopard. I feel fortunate.
I got the Leopard update and no iMac update afterwards. So I guess whatever vendor I have all is cool. Sorry others are still having issues.