Computer parts help.?

I has an emachines desktop for about 3 years and then it would not turn on anymore. Every time i pressed the power button the internal fan would start, but the computer would not start up. After that happened a friend of mine gave me his old computer, a Dell OptiPlex 210l. Unfortunately the Dell has horrible internals, 512 mb of ram and an 80gb HD, compared to my old emachine, 2 gb of ram and a 250gb HD. I was wondering if there was any way that I could salvage the parts from my old PC and put them in my new one?