I eventually found out that NVidia has a bug in their drivers that kernel panic's a Mac Pro if any memory past the 2GB boundary is addressed in the driver (from an official Blizzard poster). After waiting months for a resolution to this, I decided to post on Apple's support site. An image of my post is here.
Within a few hours, they removed it from the site, placing it under "Posts Removed by Administration". What's going on here? Is Apple trying to hide this bug, or is there something more serious going on between Apple and NVidia?"