From Microsoft KB Article 978610
Since the OP didn't really want to tell anyone.
On a computer that is running Windows 7, the usable memory (RAM) may be less than the installed memory.
For example, a 32-bit version of Windows 7 may report that there is only 3.5 GB of usable system memory on a computer that has 4 GB of memory installed.
Or, a 64-bit version of Windows 7 may report that there is only 7.1 GB of usable system memory on a computer that has 8 GB of memory installed.
Note The amount of usable memory in the examples are not exact amounts. Usable memory is a calculated amount of the total physical memory minus "hardware reserved" memory.
This is expected behavior on computers that are running Windows 7. The reduction in available system memory depends on the configuration of the following:
The devices that are installed in the computer and the memory that is reserved by those devices
The ability of the motherboard to handle memory
The System BIOS version and settings
The version of Windows 7 that is installed (For example, Windows 7 Starter Edition only supports 2 GB of installed memory.)
Other system settings
For example, if you have a video card that has 256 MB of on-board memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.
Also possible fixes include
Check BIOS settings
The problem may occur because some BIOS settings are incorrect.
Enable the memory remapping feature
Check the BIOS settings to see whether the memory remapping feature is enabled. Memory remapping gives Windows access to more memory. You can enable the memory remapping feature in the BIOS by booting to the system setup. See the User's Guide for your computer for instructions on how to boot to system setup on your computer. The name for the memory remapping feature may be different for different hardware vendors. This can be listed as memory remapping, memory extension, or something similar. Be aware that your computer may not support the memory remapping feature.
Or as OP found out, usually just on-board video.Edited by Jolting - 4/4/12 at 4:05am