On what we have here: There is only one PC (I put an Athlon X2 with 4GB in the webserver after a storm upset the motherboard in June..) with 4Gb of RAM. With the exception of the Laptop, they are all 2GB and that seems to be adequate for my own needs.

The laptop shows ( assume because of shared graphics) under 1GB. This is still quite usable on Linux but (it's dual boot) although it was sold with Vista Home basic on it, I found after firewall, a few Windows updates, etc, it is painful to use as a Win PC - does for my occasional need to try a web page in IE9, etc. but I'd hate to have to use it every day.

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re the 4GB limit on RAM with 32bit operating systems. This is a (at least certain versions of) Windows limitation. I think Linux introduced pae Kernels to address more memory around 1999.