I hate to be the fly in the ointment...but, my G4 450 renders in Bryce5 faster than it does in Bryce4. Not by much, but enough to show up in a quick test I just did. The proof is in the pudding, 8 minutes 30 seconds in B5 and 8 minutes 39 seconds in B4. I believe part of the upgrade from B4 to B5 was that it took better advantage of the Altivec core in the G4 processor. Looks like it worked out better for Mac users than it did for PC users...hmmm good reason to switch, hehe. ;-)