I have a WD 4TB external drive system for the MAC POWERPC G5 Quad. Nothing I do will allow me to see or format beyond 2TB. I can put the unit on OS 10.5 and it works fine. WD's site says 10.4.10 and higher will support 4TB. I can not find this info on the apple site. Does 10.4.11 really support anything beyond 2TBs. Thanx