Greg, thank you for your explanations. The truth is that I only saw your posts after posting mine. Sorry.
Anyway, I didn't know that the Lightwave team has split! I recently saw that a company called luxology, http://www.luxology.net, has taken over the development of Lightwave's next versions. Is that bad news or good news?
Also, from all the renderers I know, lightwave looks most FPU intensive. The rendering times depend ONLY on processor's FPU performance. Secondary level cache, memory performance, integer performance and the rest don't matter at all. In other words, instead of doing a lightwave benchmark you may as well do a MFLOPS performance measurement. This is why I thought that an implementation such as SSE2 would have a more dramatic impact.
I am a AMD enthusiast anyway and I don't feel like getting a dual Xeon. I was just afraid that AMD's chances to compete Intel in this market segment were getting short.
In conclusion, you're right, who cares about see2 when 64 bit rendering is about to arrive.
All the best.