Samsung have just created a new 16GB RAM Module now for those of us that really feel the need to have more. With 32 Bit Windows you can use up tp 4GB with Windows able to address 2GB per program, with 64 Bit you can use 128GB Ram http://support.microsoft.com/kb/946765 with a board which can support 4 of these sticks that is a whopping 64GB RAM at your pc's disposal!!!

Quote:

The chips are produced on a 50nm process, and Samsung claims that this not only means that the chips consumer just ‘over 40 percent of the power of 1Gb DDR3 memory modules,’ but that the production rate is also ‘60 percent higher than DDR2 devices of an equivalent density.’

Bit more reading here http://www.custompc.co.uk/news/604941/samsung-enables-16gb-memory-modules.html# and here http://www.guru3d.com/news/new-samsung-ddr3-allows-16gb-ram-sticks/

And for those wanting to dip their toes in the 64 Bit water as it were, Vista 64 starts at about 60 quid http://www.overclockers.co.uk/showproduct.php?prodid=SW-035-MS&groupid=33&catid=20&subcat=&name=Microsoft%20Windows%20Vista%20Home%20Basic%20SP1%2064-Bit%20-%20OEM%20(66G-02141) for the Basic Edition and about tenner more for the Premium Edition http://www.overclockers.co.uk/showproduct.php?prodid=SW-037-MS&groupid=33&catid=20&subcat=&name=Microsoft%20Windows%20Vista%20Home%20Premium%20SP1%2064-Bit%20-%20OEM%20(66I-01939)

Though you can still get XP 64 Bit it costs a good 80-90 quid and support is almost stopped if not already.