I was plagued by flikering textures on my iMac G5, then yestaday i tried the new Alpha version of the universal binary which is'nt just for intel macs it can be used on power pc macs too.....
a day has gone past and i have noticed the flickering does still occur, but is very issolated and rare..... at least its not all the time.
I reccomend using the Universal Alpha if you are annoyed with constant texture fliker!!!