I remember having one of the Original hyperthreaded S478 P4 2.4C's back in the day... it was a good chip, but the only piece of software that even recognized it was windows task manager, it showed 2 cpu graphs in the performance monitor... That was the only use of the 2nd logical core... These days with 64bit OS's and many programs supporting multi-threading, a dual core/quad core processor is a really handy bit of gear...
I still think my next system is going to be a dual - quad core box... Pure processing power. 2x quad core Intel Xeon's with 32gb of ram should pump out the photoshop work without breaking a sweat!!
Back in the day I had a dual Xeon 2 400Mhz server at home... it was the noisiest computer I've ever owned, but it was the coolest thing I have ever owned (Until the Astro-toys that is)
Ahh nostalgia..