I would like to hear community opinions on reasons to switch, to utilise, or when one should consider a x64 platform. Plus are there any additional benefits of running 64-bit Windows 7? over 64-bit Pre-Win7 OS's?
Windows – What benefits are there to running a 64-bit Operating System
64-bitwindowswindows 7
Best Answer
There are security benefits when running a 64 bit version of Windows. Basically Microsoft was able to restart with more of a clean slate and implement some extra safe guards. It is partially enabled by improved hardware support in the 64 bit CPU.
Here is a quick list of differences:
Jeff Jones has a two articles on the changes: part1, part2. Wikipedia has some information and there is this KB article (from Doubt).