When you are putting the new CD drive into the computer make sure that the
cables are set correctly and are secure. When you start the computer enter
the BIOS and just look to see if the BIOS can see both CD drives. If you can
not see them in the BIOS then shut the computer down and check that the small
jumpers onthe back of the 2nd CD drive are set to be the "Cable select"
option and try again.
It the BIOS can see the 2 CD drives then start Windows like normal, when it
has booted up properly right click on My Computer and choose Manage. Then
choose Disk Management from the left hand side coloumn and see if you can see
the CD drives in there. You might well need to activate the 2nd Cd drive or
give it a "Letter" before it will work.
Hope that this helps.