Wasn't sure where to post this....but just to let everyone know, that at the moment on Dell's site, when selecting the memory for Inspiron systems, you can upgrade from 667mhz to 800mhz memory for no extra cost - as Dell normally select 667mhz memory by default - and its generally £10 extra for the same size of upgraded memory. I'm not sure if this works with any other systems.
4096MB 667MHz Dual Channel DDR2 SDRAM [4x1024] [Included in Price]
4096MB 800MHz Dual Channel DDR2 SDRAM [4x1024] add £0.00
Mods - if this should be posted elsewhere, can you please move it!