I have an IBM 'Think Centre' desktop P4 3.0, 800fsb. It has two RAM slots, one empty, the other with a 512mb PC2700U DDR chip. A merchant at a computer show told me that PC3200 RAM would work in my machine. This made me wonder what other RAM options would work. Newer, faster RAM seems to be cheaper than a chip matching mine. Can anyone here tell me what RAM options would work in this machine, and whether the chips in each slot have to match in size, speed, etc.? Thanks.