Larry:....Unless you are going to be running some really intensive programs
then 2 gigs is more than enough to run Vista.....Although I currently run
4gigs I do not really see the difference in speed between that and 2gigs...I
would however try and put the fastest ram that is compatible with your
system.....In other words if you are currently running ddr2 667 and your
motherboard supports ddr2 800 then I would probably go for that......just my
3 cents...........Have a good one
"LarryB" wrote in message
...
Thanks Tom,

I think I understand now. It's the amount of memory "mapping" my system
can
handle that limits how much memory it will take advantage of. My system
can
only map 4gb total, and will reserve a certain amount of that for
peripheral
and system use, thereby reducing the amount of installed ram that can be
mapped and used.

So the rascal in this scenario is the computer manufacturer, putting four
slots in the case, and telling us that we can install up to 4gb of ram.
Well, we can, but the os can't use it all. :-)

Do you, or anyone, have any suggestions or tips on mixing densities, i.e.
replacing 2x512 sticks with 2x1gb sticks and leaving 2x512 in the other 2
slots, giving me a total of 3gb? Because right now I'm leaning toward
erring
on the side of caution and not doing it.

Thanks again for your response and the link!

"Tom Lake" wrote:

Question: I understand that if I install 4GB memory I will not see all
of
it. But I still don't understand whether it's being used or not. Is
it
that
the OS has reserved the memory adresses above a certain amount and that
much,
(higher), memory is just laying there, or is it that the OS is
reserving
that
memory for it's actual use, leaving the rest for application use? If
the
latter, that seems to me a good thing.

The amount above what is reported by Windows will not be used unless you
run a special program.

You can read all about it he

http://support.microsoft.com/kb/929605/en-us

Tom Lake