On Fedora 7, you can use Pidgin if you want to chat using your yahoo account.

But if you still want to use Yahoo Messenger on Fedora 7, then here's what you should do :

1. Download Yahoo Messenger for Unix from : http://us.dl1.yimg.com/download.yahoo.com/dl/unix/rh9.ymessenger-1.0.4-1.i386.rpm

2. type yum -y install gdk-pixbuf

3. type ymessenger to start configure Yahoo Messenger.

The only problem is your access need to be as 'root' then you can call 'ymessenger'

If any of you know how to handle this problem please let me know :)