[seafarer]

This idea that 64 bit computing is inherently faster and better then 32 bit is pure FUD played up by marketing types.

The sole, single, significant advantage of a 64 bit OS on a 64 bit processor is the ability to access more then 4Gb of RAM - that's it. And unless your app can, needs to and does, access more then 4Gb of RAM, then 64 bit offers you nothing superior.

And a 32 bit app is a 32 bit app, whether running on a 64 bit processor with or without a 64 bit OS.

In fact, for most apps, unless they need access to the additional memory, running 64 bit code can present a performance hit, not a gain. I have code, compiled as both 32 bit and 64 bit binaries, and on my 64 bit dual-G5 running a 64 bit OS (OS X), the 32 bit binary will outperform the 64 bit binary (same code, just compiled differently). That is, UNLESS the app can use additional RAM - me example app is a database search program. If the database to be searched is larger then 4Gb (and my G5 has 8Gb of RAM available - an obvious necessary prerequisite in all this), the 64 bit app will win the performance comparison as it can load more of the data into RAM, while the 32 bit version has to swap data in and out as it searches.

So, in terms of SHIV, no, it will not run any differently with a 64 bit OS versus a 32 bit OS.