The amount of memory your software is allowed to address is determined by operating system and the software itself, not so much the processor.  All modern Intel offerings adhere to the "EM64T" standard, which will ALLOW them to run on a 64-bit operating system, but until you make that change and you switch to 64-bit versions of application software, it runs in 32-bit mode when running software that is written in 32-bit instructions. 

Poser 7 unfortunately doesn't offer a 64-bit version ... but Vue does!

What tangible advantage over X vs. Y processor?  Check benchmarks in the link above.  It is very organic and changes month to month, who is the "best".  I stick to Intel for basically religious reasons.  People who are AMD fans are either taking advantage of their lower cost, or they are also there for religious reasons.  There isn't an easy way to look at the numbers any more and say "oh, this one has a higher clock speed" or "oh, that one has more bits" or whatnot.  It's too complex.  Benchmarking is the only thing you can even remotely trust, and even then you have to look at the parameters of the benchmark pretty hard to get some idea if it was a fair test.  Some processors do better in Application X, while Application Y will do better on the other brand's processors.

Do yourself a favor and filter out all the game performance stats.  They are meaningless when it comes to heavier applications like Poser and Vue and 3ds Max, they just don't have much to do with each other - this is why you see hard core gamers saying dual- and quad-core processors are useless, because they don't benefit games all that much (single-threaded).

re: your last post, go check benchmarks and find out :)

http://www.google.com/search?hl=en&q=quad+core+benchmark+rendering

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