Installing new drives on server

I am a fairly new net admin.,so I don’t know everything I need just yet.
I need to add two 20 gig ide hd’s to a server using both the primary and secondary ide connections. This server already has two scsi drives in it. Both are connected to a single ribbon cable. I believe I need to go into the bios to allow the system to boot off of scsi drives, or it will see the ide and attempt to boot from one of them, is this correct?
Can you give me any tips on anything else I should remember to do before I proceed?
Thanking you in advance for you help in this matter.

Michael Graziano