ScienceMark
ScienceMark is optimized for SSE, SSE2, 3DNow! and is multithreaded, as well. In the interest of full disclosure, I should mention that Tim Wilkens, one of the originators of ScienceMark, now works at AMD. However, Tim has sought to keep ScienceMark independent by diversifying the development team and by publishing much of the source code for the benchmarks at the ScienceMark website. We are sufficiently satisfied with his efforts, and impressed with the enhancements to the 2.0 beta revision of the application, to continue using ScienceMark in our testing.

The 3500+ performs extremely well in ScienceMark, but the 3400+ manages to steal a little glory in the Molecular Dynamics test.

The Athlon 64 offers more balanced performance across different code paths than the Pentium 4, and the 3500+ is no exception. Here, the 3500+ is neck and neck with the 3400+.