In order to determine the best choice in your case, you have to determine whether your application is heavy on memory or on computations. The only benchmarks in which the Xeons are ahead are those measuring pure floating-point performance. However, nowadays more and more applications have become memory-bound. It's simply easier to speed up the core of the CPU than to provide it with enough of data to process. The Opteron have an advantage here since each CPU has its own path to memory, whereas the Xeons share a single path. I would definitely go for an Opteron solution, if I had an application like yours, but I would suggest that you ask others running similar servers before. By the way, Tom's Hardware has at least two excellent comparisons of the two architectures. Furthermore, pricewise an Opteron 246 is more comparable to a 2.8 GHz Xeon. Have a nice day!!