Media Center Edition 2005 cd from Dell.. How do I take the case off. I want to

What is the model number of the computer? If it does not say on the front, it should be on your service tag on the back - if the model ends in SFF, or SL include that also. Since this is what I would do with that info, you can do it yourself... go to Dell Support page here and enter the Service Tag number from the back of the computer - from there go to Documentation. One of the documents will be the Service Guide which shows opening the case and removing and installing various hardware parts (including ram). Let me know the model number if you have problems finding the documents.
Good luck