For those of you who are curious, I just ran a little bake off between my XP x64 machine (AMD Opteron 185 2.6 GHz, 4GB RAM, Quadro FX 1600), and my Windows Vista 64 bit machines (Intel Core 2 Duo 2.4 Ghz, 4GB Ram, Quadro FX 570 & Intel Core 2 Quad 2.4 Ghz, 4GB Ram, Geforce 8800GT) in Poser Pro with the 64-bit render engine.

I was completely shocked by the results...the Opteron XP x64 machine wiped the floor with the Vista Core 2 machines, finishing my test renders in Poser Pro consistantly up to 2 minutes faster; I fully expected the C2's to beat the old socket 939 Opteron handliy. Unfourtunately, I couldn't run the test on the same machine with both operating systems installed  to account for the processor variation; I suspect they C2's would do better under XP x64. It could very well be that the Opteron runs 64 bit code better then the Core 2's and is helped out greatly by the on-die memory controller, but I think most of the preformance penalty on the Core 2 boxes was caused by the fact that they are running Vista.

There was also almost no difference between the Core 2 Duo and Core 2 Quad processors machines (both ran at 2.4 Ghz); the extra cores didn't seem to make much of a difference.

These kind of results torque me off even more about Microsoft's (and OEM builders) lack of support for XP x64...not only is the OS more stable then Vista 32 or 64, its performance seems to be a heck of a lot better. If I could reliably get drivers for XP x64 for all my machines, I would do it.

Each edition of wiondows usually has a higher recommended memory requirements. Microsoft recommend 125MB for XP and upto 1GB for Vista..It maybe partly due to them knowing the applications need more. But how much is because the newer OS needs more for the background functions. When ever I've upgraded  the OS on a machine I've usually got worse performence with a higher OS and the same hardware. I have no intention of upgrading to Vista until I upgrade to a new PC ( or that must have killer app comes out that will only run on Vista)

(Then again Poser 6 was described as XP only yet I ran it on windows ME for 18 months or more)

really? I thought they always pitched the requirements way to low myself..

Quote - really? I thought they always pitched the requirements way to low myself..

I did say Microsoft recommend. Not that I would. It would all depend on what you are using. Anyone in this forum I would expect to need more for most versions of windows

I've used Vista 64 and XP64 on the same hardware (Q6600 /P965 chipset/ 8 GB RAM /nVidia 8800GT). Results:Poser 7 was about 10% faster on XP64 and far mroe stable.
Installing XP64 on that particular machine was a bit of a challenge, it didn't work right unless I installed the drivers in a specific order. Vista was easier to install.
The Q6600 was almost twice as fast as an Athlon64 4400x2 socket 939 / XP64.

Quote - There was also almost no difference between the Core 2 Duo and Core 2 Quad processors machines (both ran at 2.4 Ghz); the extra cores didn't seem to make much of a difference.

Note that under firefly/poser, large parts of the rendering time is wasted in stuff like loading textures from disk, calculating shadow maps etc and these are all single core operations. So try a scene with no shadows, no textures and lot's of polygons... this should give you a better idea of your CPU performance, instead of being bound to HDD performance or something.

And make sure you are using 4 threads on a quad core.

echoing ghonma....did you see PoserPro rendering four buckets at the same time for the Quad?

Quote - echoing ghonma....did you see PoserPro rendering four buckets at the same time for the Quad?

I did, when I was doing some performance tests on my quads.