I can find some benchmarks that compare Opterons and Xeons, and I see lots of benchmarks that compare Athlons with Core 2 Duos, but I can't find any recent comparisons that pits the desktop and workstation CPUs against each other. I want to know how they stack up against each other and if it's worth it to spend the extra money to get an Opteron or Xeon. Thanks!
best bet would be to look for separate benchmarks that use one or two of the same tests. Otherwise I doubt that you'll find any that would compare all of those.
Also depends which Opterons and Xeons your talking about. The ones that work in the desktop sockets (such as the LG775 Xeons) or the ones that work in server/workstation sockets (such as the LGA771 Xeons)
An Opteron and Athlon with identical specs SHOULD perform exactly the same as the only difference is the grade of silicon used, which in theory would extend the lifetime of the Opteron, and is also why they tend to be very overclocking friendly(at least the 939 ones, I don't see much on AM2 Opteron overclocking). I am pretty sure that a Xeon with identical specs would perform the same as a Core2Duo with the exact same specs, because once again I think it's just the higher grade of silicon as the only difference(I'm not entirely sure about Xeons though).
If they're on the desktop platform then yes, the above post is correct.
But on the server platform (I'm not sure if this is true for the Opterons) different memory is used (for the intel platform at least, FBDIMM memory) and there are different configurations (dual socket and +)
The system as whole for the servers might be faster or slower depending on the type of benchmark/work.