update - fglrx14 helped a looooooot. I didn't know it could be installed on precise (probably couldn't back when I was still tinkering more with this machine), but with a little dependency caution, the upgrade seems to have gone smoothly.
Still not getting better than 40% cpu usage, but the error (that I think you, tank, were on a thread about - something like 0x0000028, some dev called Gregory responds and says that fglrx basically won't let him fix it) is gone for gsdx, and the whole rigmarole immediately performs much more smoothly.
Still slowing down in some places. Still other little things glitching. Haven't even gone back to try the default GS plugin, nor really seen gameplay (Waded through some intros, and saw enough improvement to at least note this. So, maybe I'm still totally housed), but the outlook is...better.
Maybe I'll manage to keep this sucker out of storage.
Edit: OH, hehe. Didn't see the additional responses. Hello Gregory...and thanks! I admit I had GSdx in software during the above. Thanks once again (do you prefer the full name?) Tank - looks like I may get away w/ just the newer fglrx...rN00?... well, 14.4 anyway.