I have a Dell Dimension 4300 that has 2 memory sockets. The Dell user's guide says the maximum memory the computer can handle is 512 mb. I guess if dell says so, it must be true. But it doesn't say if this means two 256 mb modules, or can the computer take a single 512 mb module, and if it can, why can't it take one in each socket? I've tried to ask Dell, but you really can't get an answer to a specific question at their support site.