[Edited by Squizzle, 3/8/2014 10:21:04 AM]
Since update 1.2 (Steam) there is an option to easily run 32-bit on 64-bit OS, actually for the benefit of performance too and I quote from the update notes:
- Added an option to the launcher configuration dialog to run the 32-bit version on a 64-bit machine. The 32-bit version has several features disabled causing it to use less memory, providing a smoother experience for users with lower spec machines. The checkbox for this option can be found in the display tab of the launcher options dialogue.
firewall and other security software.
on trainer and game.
version and distribution.