It's a very big tilde. My XP systems showed anything from 2.2GB to 3.5GB
before all our computers were promoted to Vista.

I use VPC extensively so I just tried an experiment to see how close I could
get to using all the memory in a computer in Windows itself. In VPC I tried
maximizing the memory allocation for an XP Pro vm in its vm Settings. I got
as high as 3.62GB to show on system properties with an allocation of 3.712GB
memory, which is the max VPC allows for a guest, on my Vista Ultimate x64
host. 3.712GB happens to be the max permitted by VPC on any host.

VPC emulates very old hardware so the reservation of relatively little
memory by the guest's BIOS makes a lot of sense. My point is that the
hardware on a computer has everything to do with how much memory is
available to user programs when 4GB of ram is installed.

btw, if VPC had allowed me to allocate a full 4GB for the guest I would
still have only gotten 3.62GB to show on system properties. It is the
addresses that are being reserved.

"Doug" <Doug <dougti@discussions.microsoft.com> wrote in message
news:OamK8kvxIHA.2384@TK2MSFTNGP02.phx.gbl...
>> BIOS and System|Properties show correct size of installed RAM while
>> System Tools|System Information and Task Manager|Performance show the
>> maximum usable part of the installed RAM. The maximum usable part could
>> be as low as 2GB. Therefor,if 4GB is installed and Task
>> Manager|Performance indicates that the Total Physical Memory is 2GB, then
>> half of the installed RAM is waisted.
> Correct. Your BIOS should tell you how much is detected, your OS how much
> is available. (In simple terms)
>
>>> 1. PAE doesn't help on Windows client operating systems, just on
>>> servers.
> Fair enough. I just did a quick google to check Windows compatibility with
> PAE. I use Unix.
>
>>> 2. The maximum accessible amount is not precisely 3.2GB
> Forgive my absence of a tilde (~)...