Everything said so far seems to point to cables. I am assuming that the CD-ROM/CDRW drives were working prior to removing the old hard disk. But since the symptoms described can result from a multitude of circumstances, the shot-gun approach is inevitable.
There are two IDE ports on the MotherBoard if this is a relatively new machine. It is beneficial to not put a CD drive and a hard disk on the same IDE channel, simply because the channel speed will default to the slowest of the two devices, and the CD device is typically several multiples slower than any hard disk.
Next point. The master/slave thing. Only one of the devices in each channel can be master, and the other slave. This is accomplished by affixing the jumpers in their proper slots. THe 2 CD drives can go on one IDE channel, one as master and the other as a slave. This will leave one IDE channel available for upto two hard disks.
Next point: The cables need to be alligned appropriately with the socket. Pin #1 will need to coincide typically with the red stripe on the cable.
Next point: I have made this mistake many many times, and spent much time trouble-shooting, only to find that I had forgotten to plug in the power source into the drive, after installing it.
(hopefully) last point: The BIOS settings. Ideally, the setting is best left in the potision 'Auto' for auto detect. Otherwise, if there is a mismatch between the # of cylinders specified in the BIOS and the actual # of cylinders in the disk, then either the disk can not be read, or its full capacity will not be available.
