I still have my PowerMac G5 (Dual 2.0 GHz with 8 GB RAM)... still works but it is stashed with my other electronics "heritage" beside a 21 inches CRT Dell flatron monitor! and the 23" Apple Cinema Display I bought with the PowerMac. Such a well built machine. I wish Apple still made such an expandable chassis but with more compatible parts like it was with the Intel based Mac Pro. I believe the one I have still has Mac OSX Snow Leopard installed, the original Mac OSX that came with it was Panther, my favorite is Tiger though.

I ran Yellowdog linux on it, and Fedora 4 back in the days when I didn't want to upgrade to a newer OS right away and I liked it.