can't retrieve mirrorlist

[unsane1]

I'm trying to tell my plesk/yum to use the atomic repositories, but I'm getting:

[root@server ~]# yum update
Loading "rhnplugin" plugin
Loading "security" plugin
Could not retrieve mirrorlist http://www.atomicorp.com/mirrorlist/redhat-5Server-i386 error was
[Errno 14] HTTP Error 404: Not Found
Error: Cannot retrieve repository metadata (repomd.xml) for repository: plesk. Please verify its path and try again

After running:
wget -q -O - http://www.atomicorp.com/installers/atomic.sh |sh