you are limited to 4 eide devices total. If you only have one optical drive then just put it on the chain with your hard drive. Always use cable select. You could also buy a pci card that would give you more drives.

They probably word them differently by manufacturer but it would be just like this.

thank you.  What will the PCI card called ?

yes it will all work and is all cross/backward/forward compatible. The only thing is that if you have one ata 100 and one ata 133 on the same channel, they will both run at the lowest speed (ata 100). They will still run though.

Thank you for your reply again.  I really appreciate that.  Is it possible to add UATA 133 controller card connected to one UATA 133 harddrive with 2 UATA 100 harddrives already installed in the system ?