That still wouldn't explain the massive difference between the rendering times. Those old Athlons aren't THAT good. Just look at the busses. That's 133 megs versus 400 (or 800 if you look at from the dual channel mode). Even if the Athlons were that good, the buss would hold it back. The fact that the Vue render times on the P4 without HT on is so miserable has to do with Vue not optimized for the architecture. I shut HT off again and ran the Photoshop tests again and the P4 machine still smokes the Athlon. All roads lead back to Vue. I don't doubt however, that Vue will run better on an Athlon if I had built, say, an XP 3200 system (or even an Athlon 64). I probably would've recieved another 50% or better increase in performance. But that's because it's an architecture that Vue recognizes. There's something about the P4 and/or the 875 chipset that's freaking Vue out.