Actually, the 2GB limit I made mention of was referring to how much memory the 32 Bit versions of Windows Operating Systems can allocate to the OS and to programs. It's 2GB of memory space for the OS, and this is a hard coded limit, and 2GB memory space PER program, regardless of how much memory is actually installed. You can set a /3GB switch in the boot.ini and/or the BCD file to allow programs to access up to 3GB of RAM, but then you're reducing the available memory space to 1GB for the OS.
And, since 32 Windows can only address 4GB of memory space, you'll never have access to all 4GB of installed RAM since due to the way memory is allocated and the way drivers are loaded, they reduce the amount of physical RAM that is available to the OS and to programs. If you install a video card that has 2GB of VRAM, that 2GB is subtracted from the 4GB memory space that 32 Bit Windows can address. So, you're shooting yourself in the foot if you want to use high-end video cards and sticking with a 32 Bit version of Windows.
Here's 2 articles that detail how this works: http://en.wikipedia.org/wiki/3_GB_barrier
http://www.dansdata.com/askdan00015.htm
If you want access to ALL the RAM you have installed, you NEED to use a 64 Bit version of Windows. It doesn't hurt performance for 32 bit programs. They can run just fine under 64 bit Windows on modern processors. If you are using an Intel Itamium, you will see a performance reduction for 32 bit processes since that processor can't run 32 bit code natively and has to run it in emulation. But, those processors shouldn't be something that someone would use to build a Watchout system.
I hope this clears things up.
Dr. Z