I use a Fire Modelling CFD package called SMARTFIRE at work. It can be run in serial or parrallel. Does anyone have any recomendations for the optimum desktop computer spec? considering getting 2x Quad Core Zeons and running in parrallel on the 8 processors. Any comments?

This sort of question has been asked often on this forum, so have a search through the history banks. The short answer is that you HAVE to test YOUR software if you need a definitive answer. Arbitrary benchmarks can be misleading, especially when issues like memory or cache usage and latency become important. There are lots of caveats to consider before blindly believing the SpecFPRate figures (www.spec.org , look under SpecCPU), but in my experience these at least give you a reasonable idea of how parallel processing is likely to scale on your system. From the SpecFPRate figures I would tend to steer clear of a 2Xquad-core system, it seems to offer surprisingly little performance advantage over a 2Xdual-core. This leads one to suspect that it's severely memory bandwidth limited. If you really need an 8-way system, either consider a small cluster of 2 dual-socket dual-core machines, or, more cost-effectively, 4 single-socket dual-core machines. If there is some reason why you really need to have an 8-way SMP system (as opposed to a distributed memory cluster), the better option seems to be a 4-socket dual-core Opteron setup, which, according to the SPEC figures, has much better parallel scaling.