I think we're missing out the big picture here.

Any 32-bit OS cannot address more than 3072MB of RAM.
So the only reason to get 4GB would be to either have 3GB under 32-bit or 4GB under 64-bit.
Now, I am very much interested in the latter. My concerns are:

a) Will my current favourite 32-bit programs run under Vista 64-bit?

b) Do any of the applications that could actually make use of so much RAM ( Games, Video editing) come (or will eventually come) in 64-bit versions?

e.g. are/will there be 64-bit versions of Nero Suite, Adobe Suites, Crysis?

Windows has an API called AWE (Address Windowing Extensions) that allows access to multiple regions of extra memory simultaneously. I have never used it myself but from looking it over, I gather the extra memory is mapped into the existing 32 bit virtual address space so no, a 32 bit program would not be able to access more then 4 GBytes (minus what the OS is using) simultaneously. It looks a lot like a more sophisticated version of EMS memory mapping from the DOS days.

http://msdn2.microsoft.com/en-us/library/aa366527.aspx

They really should express latency in nanoseconds.

LOL, funny how CAS4 is considered 'low latency' nowadays. so sad.

Yeah, 4GB of DDR2, just in time for the DDR3 hype to begin. I'll wait.

what, no DDR3?

holy crap, i haven't even made it to 2GB let alone 4.

500$ ...................

I want reasonably priced 2gb modules, but not for Vista.

That seems way way expensive. XMS 2-gig DDR2 4-4-4-12 was $240 the other day at newegg and came with a $40 MIR = $200.

Whew, just in time for Vista

Who cares about low-latency RAM? It's not worth the money.