I have a Phenom II X4 945 and a Radeon 4870 from 2009. I bought it for Dragon Age Origins - and it still does the job.
For me a user.cfg file, disabling some graphic options made the trick of getting the CPU down to playable. To me it seems obvious that 4 cores running 100% all the time is unneccesary - but I do understand that programmers with a deadline don't have time to optimize code to reduce CPU, and that games that use 100% CPU most of the time helps selling new and faster CPUs and GPUs.
From this forum I get the impression that human value can be measured in GHz, and that pepole with old systems are not really to be taken seriosly. If you refuse to post your vital measurements, you should feel ashamed, it's like not taking off your shoes in a american airport security control.
lemastertrole has my sympathies, most of all for not giving up after 2 months, but also for keeping an old system alive. Still, if you are below the minimum requirements, I am afraid your case is lost. If you are just above (like me) there is hope, but you have to look around this and other forums for tricks and tweaks to reduce CPU. If your CPU peaks, your GPU may be working on old and illegal data.
Bioware is a great studio, making unforgettable games. I was however happy with the graphics of Baldurs Gate - 2 that would be, 1 was too buggy at first - and I wish for any future DA 4 to keep up with good storytelling without frying "old" computers by forcing everyone to calculate how individual high quality leaves move in the turbulence of wind.