All the above drives, are placed in the 5.2" bay in the case. They are usually attached to the IDE connection, and the sound card (audio from CD's/DVD's). 

All drives today will be able to CD's, and the CD-RW's will be able to write &/OR re-write to CD's. The speed is quite important, for reading; CD's above 32x is good, DVD's above 4x. Writing to; CD-R's, above 4x (best so far-12x), CD-RW, above 4x (best so far-10x)

Burn Proof technology is now available for a number of CD-RW's, this stops buffer underuns, the cause of wasted CD's. Such CD-RWs with Burn Proof technology are; Plextors, 12/10/32A, so far the fastest CD writer available.

For DVD drives you'll need a pretty descent graphics card to work with the zoom modes and actually playing the high detail levels on DVD.

Floppy drives...

The oldest part in new PC's, 1.44Mb storage space, cheap at 5-£10.