Dual processor VS single higher clock speed processor Xeon

Our current systems are Core 2 Quad 9550 2.83GHz running XP pro 32bit SP3.

I am considering going to a Dual Processor Quad Core Xeon E5520 2.26GHz. Still would need to use XP 32bit. My thinking is that our biggest bottleneck is the amount of time we spend rendering in Photoview. Since the time to render is directly tied to the number of cores in the CPU and number of CPUs I was going to spec out the 2 processor machine. Also the new Xeon uses Hyperthreading and acts like an 8 core machine.

What I would like to know is if anyone has tried a dual processor Xeon yet with Photoview. And yes, I already looked at solidmuse.com and there are no test posted for a dual processor Xeon. Also, I wanted to know if a Single processor Xeon(3.2GHz) would be a better choice as it should give better rebuild times in solidworks. The last question is weather or not XP 32 bit is going to limit the ability of benifiting from a 2 processor machine.

Thanks

SolidworksPhotoview 360