Probably your notebook share system RAM with the Graphic Card (can be 1-2GB)
If you have more ram (>=3gb) installed on 32 system, you can create ram disk that can access rest of ram. E.g. you have 6GB, system use 3GB, so you can create 3GB Ram disk where you place windows swap file, temp directory.. So you use all of your memory.
Or you can try this:
Windows 7 32-bit with full 4 GB or 8 GB RAM support
Code:
http://www.unawave.de/windows-7-tipps/32-bit-ram-barrier.html?lang=EN