I want to add memory (ram) to my computer, i checked in the system report using PC Wizard 2006 that i have:

Dimm 1 (Ras 0, Ras 1): 128 (Double Bank)
Dimm 2 -empty

Controller: dimm, sdram
2 controllers
max module size: 512 mb
max memory size: 1024 mb
supported speed: 70ns, 60ns, 50ns
Supported voltage: 3.3v

So my question is...is my information for my vendor enough for me to buy the correct one

1 512MB Dimm Sdram 3.3v (70ns, 60ns, 50ns)

do i need to specify if doublebank or not? Can i add 512MB to a 128MB resulting to 604, so is that value possible (i'm thinking that it should be 256, adding up to 128 only)