jternorj, I don't agree on most of what you wrote.
1. indeed, 16-bit apps are limited in 64-bit (limited, because there are some 32-bit apps that are installed using 16-bit installers)
2. 32-bit windows desktop os is limited to 4GB RAM. Windows Server editions, linuxes, unixes and whatever can use up to 64GB of RAM in 32-bit mode using PAE (check wikipedia). Only apps are CPU-limited to 4GB, and actually 2GB of application data.
3. 64-bit windows requires signed drivers. So developers of drivers have a harder time (think about oveclocking/monitoring tools)
4. having a 3GB GPU (or 2x1GB) will not reduce the RAM availability in 32-bit windows (do you actually have a 2GB GPU under 32-bit windows? or did you just scaled the numbers you read?). I don't know exactly how the rule is, but not all of the VRAM has to be mapped. Through a 512MB window you can access 3GB or VRAM (or more).
5. Not many games have 64-bit executabled. When they do appear, their main advantage will be speed optimizations, not memory usage.
So, to the OP question, for the current games (no 64-bit binaries), there is slight advantage of 64-bit which comes from optimized GPU drivers (but I would say under 5%). For strictly gaming setup, 3GB of RAM is enough until 64-bit games get mainstream. Few game benefit from /3GB switch (which does allow using of 3GB game data), so 2GB for games and 1GB for kernel+cache is enough for the next year. So if you need drivers for old HW (which is buggy or inexistent for 64-bit) or have 16-bit apps/games, stick with 32-bit (although you will not use half of your RAM).