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).
I think your Sony Vaio RS210 uses the older style IDE CD and DVD drives - not the newer SATA models.
It looks like your case has those color-matched-to-case fold down DVD covers that hide the actual drive.
After you take off the left and right side panels of your case I think you should be able to remove the entire front face plate.
Behind that you'll see the actual bare DVD drive. From there it's as jsc says. Remove a couple screws, detach a few wires and slip the old drive out, and the new drive in.