Ok so here is the latest update.

I have 4 Desktops ready for testing.

1 Machine needs a new processor but for now I'm going to use it to manage the actual render jobs.

3 Machines have identical specs:
Intel Pentium 4 CPU 3.00GHZ / 2.99GHZ / 512MB (Yes I know ram is low)

I built these machines with the focus on processing speed and are running on very highly optimized versions of XP with a very small foot print.

All unnecessary programs / system files / processes have been stripped out.

I have attached a screenshot to illustrate how highly optimized these PC's are.  

You will notice that only 15 Processes are running at anytime, and only 82mb of RAM is in use, if you want a comparison, if you are a Windows User, do a CTRL-ALT-Delete and take a look at the task manager.  You will probably have 30 Processes running if not more, and probably using up 512mb or more.

So I need to buy a few things off ebay, Processor more RAM and 1Gigabit switch.

In the meantime I'd like to start testing.

What do you guys recommend? Should I just jump and install the latest Bryce 7 Beta and test with that?  6.3? 6.1? 5.5? 5.0?