What Happens when 3GB or more RAM is installed With Windows?

3GB or more installed RAM can enhance performance and it is now affordable. This paper examines what happens when 3GB or more RAM is installed in conjunction with Microsoft Windows XP or Windows Vista on x86-based computers, including HP Personal Workstations. It is important to understand that the Windows XP Professional or Windows Vista limit available RAM to noticeably less than 4GB while Windows XP Professional x64 Edition and Vista 64-bit can eliminate this barrier. Microsoft Windows XP Professional and Windows Vista are 32-bit operating systems supporting a physical address range of up to 4GB. However this range is sub-divided to manage both the computer's PCI address range (also known as MMIO) and RAM.