On my new PC setup, I am running TMPGEnc to do some DVD encoding, and the highest CPU utilization rate I get is 50%. This is on a PC running XP (P4 2.6c, 1GB RAM, Abit IC7-MAX3, and plenty of disk space - 300GB+). I've also closed down extraneous programs, etc. It's running pretty lean, but that doesn't seem to matter since it's got CPU cycles to spare running at only 50%. On the TMPGEnc side (options -> Environmental setting), I have all the CPU boxes checked except for the Multi-processor option, and I've tried checking the box with no change in CPU utilization. For the Task Priority, I have the High priority selected for active/non-active window. On my older PC (Celeron II 1GHz, 512MB RAM, Asus CUSL-2 MB, 100GB of disk space free) running Windows2000, when I run TMPGEnc, it'll hog the CPU something fierce (though running at full speed, its encoding speed is at least 3 times slower than the new PC).