PC Does Not Show 4 GB Ram In Windows XP

We are Know That By Default 32 - Bit Windows Xp Supports Only 2 GB Ram And 64 - Bit OS is Supports 4 Gb Ram.

But 32 - Bit OS Can Support Up to 4 GB Of Ram

But How ......... ?????????    I tell You About It

Open BOOT.INI File From Your Pc In Notepad
and Edit It As Well As

 After /FASTDETECT 
Add A New Word As Well AS

/PAE

Save It And RESTART Your System

((((((((((((((()))))))))))))))))))))))))))))))

IF You Using VISTA  Os Then

Open CMD
and Type Here

"BCDEDIT / set PAE forceenable  "  And Press Enter
Restart Your System