Help with cdrom

Question

I am currently trying to put a new segate hard drive into an olderl compaq presario. It has an amd 550 in it . It also has a burner and a regular cd drive in it. No other drives. On install, I can't get it to recognize the cd's so that I can boot from them. They do not show up in the bios either. I also get the ntldr missing message. Can you offer some suggestions?