Thanks for your advice. I could only get at the memory. I was unable to remove the back panel. I looked at the users manual, in PDF, and looked at the types of CPU, motherboard etc (for each of the 4 models) and compared wit with what control panel showed and with 9410Z and concluded that it would max out at 2GB and that it does support dual channel mode. Then I called a local brick and mortar store and asked them I want to try their 2GB and 4GB dual channel memory and that I would return it. THeir memory is quite pricey. When I put the 4GB memory, the laptop would just wait.... and wait after power on. Nothing happened for a few minutes. I turned it off and checked to see if the memory modules were seated right. and turned it back on with the same results. Then I tried the 2GB dual channel memory and powered the laptop. It started like a charm. It works better with multiple applications and turns off much quicker. Thanks for the advice, once again. BIOS, as well as control panel and CPU-Z recognise 2GB. How do I tell if it's working in dual channel mode? I think it is, becuase if it were not, 2GB would not be faster than one GB, if the oriignal 1GB was operating in dual channel mode. However, if the originally installed memory and the new 2GB memory are both NOT operating in dual channel mode, I would see the improvement. Is there anyway to tell if it's running in dual channel mode?

Thanks, once again.