It's a desktop system, so all you should need to do is open it up unscrew the 4 mounting screws and unplug two cables and slide it out.
Underneath, all DVD/RW drives are pretty much the same. Some brands are more reliable than others. I like Samsung and LG.http://www.newegg.com/Product/Product.aspx?Item=N82E16827151188http://www.newegg.com/Product/Product.aspx?Item=N82E16827136168
Prices at a BestBuy will be a little higher.
The only problem may come if you want to maintain the look of the computer. You should be able to change the faceplate from the old drive to the new drive. If you cannot change the faceplate, a Sony part will be about 4 to 5 times more expensive ($150 instead of $30 - $40 if you don't mailorder from newegg).
Check this "Build it yourself" article:http://www.tomshardware.co.uk/forum/274745-13-step-step-guide-building
And look at where he installs the optical drive. It's pretty simple.