Yes, if the current drives are attached to the same ribbon, just remove them and replace with the new ones. Make sure one of the new drives is set to master and the other slave. (Copy the jumper settings of the old drives.)
However, it's best not to have both drives on the same channel, especially if you intend to copy from one to the other. If you have an IDE drive already, then you can slave one of the DVD drives to the same cable. Again, you need to make sure one of the devices is master and the other slave. This may involve altering the jumper settings on the hard drive, depending on manufacturer. The other drive can sit on the Secondary channel as a master .
If you have more than one IDE drive, then put one of each channel with a DVD.
If you have no IDE drives, then put one DVD on Primary and the other on Secondary IDE channels and set both to master.
A footnote to jumper settings. There is a third option, called cable select. In theory, if both drives on the same channel are set to cable select, then they will sort themselves out according to their position on the cable. I avoid this setting as it can be unreliable.
Liteon drives are considered a budget option, but i've not seen any particular problems that other more expensive drives don't get.
