Trying to toss an old computer together for the g/f to use while her laptop gets fixed. I have 5 sticks of ram but none are matching. 1. Corsair 512MB 400MHz 2. Kingston 256MB 266MHz 3. Elixir 256MB 266MHz 4. Micron 256MB 266MHz 5. Nanya 256MB 333MHz the tower I'm going to use has 3 RAM slots. Was hoping I can run the 512 and two sticks of the 256. Possible?