This is a really good read from Tom's Hardware. Find the full article here: http://www.tomshardware.com/reviews/64-bit-vista-gaming,2250.html Conclusion We know that testing 64-bit platforms against 32-bit platforms in a handful of gaming scenarios is not a brand new concept. It was done several times back when Crysis launched, and even before that in 2005, when AMD pushed a patch adding 64-bit compatibility to Far Cry. What’s interesting, though, is how far we have (or have not) come with regard to pushing native 64-bit computing in the latest games. Given the benchmark results, we’re not altogether surprised, either. With the exception of Grand Theft Auto, none of the games we tested demonstrated any appreciable speed-up. But this is to be expected, according to a wealth of performance data posted all over the Web and confirmed by the IHV and ISV representatives to which we spoke. The magic of 64-bit computing isn’t what it does for performance. Rather, the real story is what it does for game while it’s in development and then for stability when it’s in the hands of the gamer. Of course, you must remember that a 32-bit application without /LAA enabled is still limited to 2 GB of virtual address space, even in a 64-bit environment. However, we’ve seen plenty of examples of technical gamers modifying executables to turn the large address aware flag on. Sixty-four bit adoption started off slow and is still trudging along. According to Terry Makedon, head of AMD’s software product management team, just over nine percent of Catalyst Control Center downloads are of the 64-bit variety—the audience is still relatively small. However, as the price of memory falls and 4 GB becomes the de facto capacity at mainstream price points, 64-bit operating systems become necessary, if only to utilize the hardware’s full capabilities. As the shift to 64-bit accelerates, expect a greater number of developers to start shipping native x64 titles. At that point, there will be performance gains to be had, according to Microsoft’s Chuck Walbourn, through utilization of the extra registers, better SSE2 SIMD utilization, aggressive use of memory-mapped I/O, and significantly larger game assets. The bottom line is that you won’t see game-changing benefits from the apps you play today. But when you consider that a 32-bit Vista license already entitles you to the 64-bit version, that memory is cheaper than ever, that properly recognizing 4GB or more requires a 64-bit OS, and that even 32-bit games with the large address aware flag can benefit from extra system memory, the decision to go 64-bit should be an easy one. We’ll even take our own medicine. Many of our most recent reviews already employ 64-bit environments, but in the weeks to come, expect to see a benchmark revamp, where we shift as many of our tests as possible to the latest 64-bit versions.