Smooth - thanks very much, especialy for the detailed information.

Everyone else, thanks for the replies. The cost is prohibitive and a single SSD with an increased page file size would seem to be cheaper (not sure if it's better though).

I used the tweakwow addon to increase the texture cache size to 512mb (single boxing this improves dalaran performance a lot) so 5x512mb plus the normal memory load plus >50mb of addons so far means I'm often >5gb memory used.

Would it be safe to assume that the price difference between the 2gb and 4gtb ddr3 modules is purely down to volumes manufactured and sold?