I have inherited my wife's old HP laptop (I bought her a new one.) I will eventually upgrade it from Vista 64 to Windows 7, but want to upgrade the memory before I do that from 4GB (2 x 2GB) to 8GB (2 x 4GB) first. I know how to replace the memory sticks, but have never actually bought it. Any recommendations where to buy the memory sticks? For what it is worth, I need 2 x DDR2 SODIMM 200pin 4096MB.