This is one of those topics that keeps popping up and can be answered by
"reviewing" previous posts.

Article #929605, Support.com, addresses all your questions including a "Work
around". Following are two quotes from the article:

1. The reduction in available system memory depends on the devices that are
installed in the computer. However, to avoid potential driver compatibility
issues, the 32-bit versions of Windows Vista limit the total available
memory to 3.12 GB. See the "More information" section for information about
potential driver compatibility issues.
If a computer has many installed devices, the available memory may be
reduced to 3 GB or less. However, the maximum memory available in 32-bit
versions of Windows Vista is typically 3.12 GB.

2. WORKAROUND
For Windows Vista to use all 4 GB of memory on a computer that has 4 GB of
memory installed, the computer must meet the following requirements: (note
therre are several "steps" listed in the article - one of which must be a 64
bit processor).


"JC" wrote in message
...
I have 4GB of physical RAM, windows vista shows only 3326MB. Does it really
help with performance if I have 4GB or should I just install 3GB memory? I
just bought the additional 2GB memory (had 2GB before) and wondering if I
should exchange for a 1GB one. Thanks.