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RE: 3dnow

>2. I downloaded the Atlas 3.3.1 developer snapshot and built it using GCC
>3.0 on the aforementioned Athlon, selecting the "3DNow2" option and letting
>it grind overnight through all of its tests. The "SUMMARY.LOG" file is
>attached; I have all the other files if anyone is interested. It takes about
>eight hours at 1.333 GHz, BTW.

Have you tried to say "yes" to architectural defaults?  My guess is that it
will get you better performance than what you are reporting.  The search
script needs some hand-holding on Athlons to get good results.  This is
due to the fact that the hardware uses seperate multiply and add units, 
but due to the register pressure and renaming stuff, you nonetheless need
to program matmul like you have a combined muladd FPU.  Since ATLAS detects
the seperate multiply/add unit, the gemm search is non-optimal.