I have an old Gateway ESS450SE. I would like to gut it out, use the case, and rebuild the computer. Is that possible or easier to just buy a new case?
Can you post a pic of the case?
If it is a standard ATX case, then you probably can.
Do you love the case? If so, go ahead and try.
If you don't look for something that appeals to you. It is the part of the PC that you see and touch every day.