Whilst memory is so cheap is it worth buying the OCZ 2Gb (2x1Gb) PC2-6400 on special at the moment to go with the current 2Gb I have? I am running WindowsXP Pro with service pack 2, and as far as I know it will only see 3Gb of it, but I might make the move over to 64 bit Vista after Christmas is out of the way.