http://support.microsoft.com/kb/929580

A 32-bit operating system can address memory that is relocated above the 4
GB boundary if the following conditions are true:
• The computer is in Physical Address Extension (PAE) mode.
• The computer has 4 GB of RAM.
In this case, the operating system correctly reports how much memory is
installed.

To enable PAE mode, you have to add PAE to the boot entry in the BCD file.
Open an elevated command prompt. Type BCDEDIT /SET PAE ForceEnable.

I did this and checked to see if pae was set to forceEnable but typing
bcdedit, but it didnt work. any suggestions? why