I would like to add memory to a new HP pavilion a720n that came with 512 mb pc2700 ddr sdram according to mfg specs on box. I am confused about ordering more memory after finding that ddr ram comes more than one way for example registered & unbuffered .I would like to add another 512 mb, looks like mobo has another slot open. Could someone help me sort out what I need to buy and recommend a good source? Thanks,Dyno Wanna kill these ads? We can help!