32 bit Windows memory support

This subject has come up on several occasions, so I'm posting a note with several references on the topic.

Basically, 32-bit Windows desktop operating systems (XP, Vista) will not address more than 3 GB of installed memory.  You can add the /3GB switch to your BOOT.INI file, but hardware constraints, including your video card and BIOS will limit how much RAM above 3GB is available for the operating system. 

NOTE:  This is particularly an issue for high end video cards because the amount of video RAM is deducted from the 4GB theoretical limit for 32 bit operating systems, so even if you have 4GB installed, a 512 Meg video card could reduce your available ram to under 3GB.

Microsoft MSDN article: Memory Limits for Windows Releases

Microsoft MSDN article: 4-Gigabyte Tuning

Dude, Where's My 4 Gigabytes of RAM? - this article includes a nice Intel map of the 32 bit address space memory allocation details.