With help from this forum I finally set up 4 render cows, plus installed a cow on the main machine for my limit of 5. All are 7.2 build, all are at least dual core and 2 to 4 gig of ram each. I'm on a private gigabit network, all pcs connecting at gigabyte speed. Vista 64, 64, 64, vista 32 and xp 32  in total.
I did a high resolution 30 second animation with 4 cows plus the cow running on the content creator and SNOOZE SNOOZE!!!
They spend so much time communicating, the rendering of each frame is only about 25% of the total time. With all five machines going the video took  24 hours to render whereas the solo quad core content creator rendered the same video in 30 hours. It seems like I just wasted time and money setting up this farm.
Now I also noted that the quad core vista 64 machine that runs all 4 cores at 100% in rendering alone only runs the cores at 25% when acting as a cow.
There is no info in the manual about optimizing (or cutting down on) overhead. Is this just the way it is?

One upset Farmer John

Hmm....

1. The cows are, by default, designed to run as background services, so anything with a higher priority will slow it down (even a screensaver). Go into your OS performance settings and change the priority from foreground to background.

2. I didn't think that the 32 bit cows would work properly with command and data feeds from a 64 bit manager; and even if it did, it would require dumping all the data in to the swapfile and running some kind of virtualized addressing to get around the limit of the 32 bit address bus. Try the video again, only this time leave the 32 bit machines out of the queue, and see how things perform.

3.  Are these dedicated renderslaves, or are they actual personal computers in use by other apps and people?

1. How big is the scene in megabytes? If a Cow lacks the physical ram to process a frame, then it hits the swapfile....hard.

2. Are you absolutely -certain- that all your hardware and cables are rated for gigabit? One bit of hardware not up to it will cause the entire thing to slow down to the fastest stable speed. A friend was setting up a gigabit home network, and nearly went crazy trying to find the reason the best he could get out of the whole shebang was 10/100. It finally turned out that one of his patch cables was an unshielded Cat 5, instead of a Cat 6 shielded, and the router it was attached to detected the unstable signal and impedance mismatch and throttled things. Static tests were fine, but real world use would trigger the slow down....

=How= the scene is set up  can have an effect; not all things in Vue are multithreaded, or able to take advantage of all available threads. How long was this animation in frames, what format was it created in, and what were your render settings?

1. They are desktop PCs but not used for any purpose other than rendering, while rendering. I will try with optimizing for background services and turning off sidebar cpu utilization monitoring  screen saver etc.
   2:  I'll drop the 32s and try again. 1 can be upgraded to 64bit, 1 can't,
2. How big in Meg? do you mean the saved  .vue is about 100mb, is that the question.
   5.  I'll check the cables, I think they are cat5e. The dell switch has good management. but I haven't tried tweeking it, it was just put in to share these pcs.

The scene is Poser7 and Vue  ecosystem plus imported objects global ambience.

I pushed the quality up to broadcast 900 frames 800x600. I really just use final but i wanted a longer render time to see the difference between the 2 methods better.
thanks

The rendercows are not very efficient. Also, make sure NOT to use the "Force Tile Size" option, as multithreading takes a real nose-dive if you use it.
I don't think the the 64-bit vs. 32-bit OS would matter that much, but that would depend on how well the programmers did their job. I have a Mac Pro 8-core with Vista Business 64-bit and 14 GB of RAM as the "client" PC, and use 2 Q6600 PCs as dedicated render nodes -- each with 4 GB and Vista 32-bit.. I find the rendercows to be not very efficient at all.
When running multithreading on top of network rendering, you really need some well written code to make it all work well. I think I'll do a bit of testing to see if the 64 vs. 32-bit OS makes much of a difference.