External device, as a problem with the operating syteem USB set up- so in my opinion which to buy is academic.
To quote an example.
I have two desk top machines one has only a CD reader,whilst the other has a DVD/CD read/writer.
I occasionally neeed to read/write a DVD on the one with out.
So this is what I did
Removed the Writer from the machine and invested in a USB/Cable and power supply -Approx £12
Set the device to Master and switch it between machines via the cable as required.[thus it became an extrernal device.
Both system are XP Pro.