windows 32 bit & 64 bit no difference to me ?? why

i have intel 945 board (dell gx620) and i have dual boot up of xp 32bit
with newly installed windows 7 64bit..
But my computer is showing 3.5gb ram out of 4 on BOTH WINDOWS. I installed windows 7 32bit first and was happy with it but as soon i read the CLAIM that
"64 bit version utilizes ram more efficiently means FULL available", so i updated my 32 bit old Cpu to "inter D 2.8 ghz 64 bit" and installed Windows 7 64bit BUttt
still 3.5gb available???? this is f*** up now Lol

so all windows ( Xp 32 bit,, windows 7 32 bit and 64 bit) are showing EXACT SAME available RAM....then y to have 64 bit windows ??


is every board out there cant show 4 out of 4 gb ram in 64 bit, or its just me...??

Cheers

Chipset/bios limitation. The old Intel 945 chipset only supports up to 4 GB which makes it fall under what is described here (just change the 8 GB to 4 GB),

The system memory that is reported in the System Information dialog box in Windows Vista is less than you expect if 4 GB of RAM is installed

Note When the physical RAM that is installed on a computer equals the address space that is supported by the chipset, the total system memory that is available to the operating system is always less than the physical RAM that is installed. For example, consider a computer that has an Intel 975X chipset that supports 8 GB of address space. If you install 8 GB of RAM, the system memory that is available to the operating system will be reduced by the PCI configuration requirements. In this scenario, PCI configuration requirements reduce the memory that is available to the operating system by an amount that is between approximately 200 MB and approximately 1 GB. The reduction depends on the configuration.

So i don't need to keep 64 bit version? As windows 7 32 bit shows same amount of ram !! ...or still 64 bit will be better for my specs??

If the 64 bit is working I would just leave, that is unless you feel like having to completely re-install everything just to go back to 32 bit.