My system has a Samsung DVD Rom (SD-616T, came with the computer)and I later added an LG CD RW, these occupy the only two bays. I am about to buy a BenQ DW1620 DVD writer and wonder whether to replace the DVD Rom or the CD Rw. Probably an idiots question - if so apologies from a beginner! ps Anyone like to comment on the BenQ - or suggest better (for the money!!).