CS 5.5 / Nvidia / Mac Pro (3.1) question

I'm trying to find an answer to a compatibility question with my Mac Pro (3.1) and Nvidia.

I looked at the Adobe tech req's website (http://www.adobe.com/products/premiere/tech-specs.html) BUT...

It says:
"Multicore Intel processor with 64-bit support"

The 64 bit "support" has me thrown off.

I'm running a Mac Pro (3.1) Quad Core Intel Xeon 2 x 2.8 with 8GB Ram and OSX 10.5.8. So I'm pretty sure that my processor is only capable of 32bit... Does this mean I cannot run CS 5.5 or an NVidia Quadro 4000 graphics card??
If I can run the software & use the Nvidia graphics card - will I be able to take full advantage of the software if my machine can only run 32bit?

Many thanks in advance!!

Adrian

Think solutions!

All Mac Pros have 64-bit processors and OS X 10.5 is capable of running 64-bit software. However, you will get better performance by running it on Snow Leopard.

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