To install both DVD-RAM and DVD-ROM into a single PC you need a USB drive unless you install it in a desktop with an open 3.5"" drive bay and an open IDE/SATA connection with a power supply that can power it.
The PSU should be able to provide the power itself.
to install it in a tower:
1) turn off and unplug the tower
2) unplug all cables from the back of the tower
3) remove the screws on the back of the case and remove the cover.
now it is time to see if your pc will accept the drive.
4) look in and see if you have a dvd drive already installed
5) if so look right below it or right above it.
6) if it looks like one will fit in there(with a little space), then you may install one, otherwise get a usb drive
to install one:
7) while you have it open identify the ide/sata connection cable and your power cable. you also need to put the second drive in slave mode. to do this read the manual that came with the drive.
8)break away the cover covering the expansion bay front
9)insert the drive, attach the cables in their representative spots, and they will fit only one way, and screw in the bay holding screws.
to close the case back up:
10) put the cover back on and snap it into place
11) reinsert the screws for the back cover
12) set it back up and plug all cables back in, then start up the tower.
13) windows should automatically detect the drive and install the drivers.
14) put a cd in and see if it registers.
15) if it does then you are done!