I ordered an internal LG blu ray drive for my 2008 model, along with a PATA converter so I could replace my DVD drive (which doesn't burn some media anymore). However, burns either erred off or locked up the computer.
The drive put into a different computer where I could use SATA worked fine, so it is the adapter.
I'm going the route of an eSata card, and an external enclosure, to see how that works. These extra parts are on order.
I didn't want to go through the effort of trying to access the extra SATA ports on my Pro. If you are willing to do this, or have drive bay ports available, then that is probably the way to go for internal use.