we had about a 50% success rate upgrading older G4's to new Sonnet dual processor cards. Out of 5 upgrades, 2 of them became unstable for whatever reason.
recent decision has been to simply replace all the g4's in the office with new G5's - dual processor desktops for the design and production staff, and iMac G5's for the project managers who don't use CAD very much.
Multi-processing is really only useful when running multiple programs at once (like AC, PM, BGAC and your other typical programs). ArchiCAD on its own does not use the dual processor capabilities with 8.1 or 9 (no official v8.2 exists to my knowledge - is 8.2 your name for GS's moronic numbering system?)
hth
wes
