Dell has some outlandish prices on their replacement parts.
I suggest jumping on ebay or using newegg. Laptop optical drives are fairly compatible, but verify this before you spend money. It could be an issue.
http://support.dell.com/support/edoc...0/en/index.htm
HTML Documents ->Service Manual -> Download*
It's a zip file, unpack the files and open begin0.htm
Read this page, take out the battery like it says.
Scroll to the bottom, Click the 'Back to Contents Page' link, then click optical drive. There should be one or two screws that hold the unit in place. The optical drive page contains the instructions necessary.
*I couldn't get the web view to work, it would timeout.
Good luck.