The core-for-core thing makes a huge difference in the real world that doesn't show up on single-core benchmarks. The HT660 was a good chip in its day, but it's at a four-to-one disadvantage for code that's multithreaded and/or running on a busy PC.

I think Sandy Bridge is my favorite CPU of all time. It does a truly massive amount of work without consuming significantly more power than the part it replaced.