I'm trying to make an old iMac G5 (17" 1.8ghz non-iSight model) of mine useful again and am giving it to my mother, but after adding another 1gb stick of memory (making it 1.5gb total), putting in a new 7200rpm 500gb HDD and upgrading it to 10.5, I'm experiencing stuttering youtube in Safari and general sluggishness. Could it be possible that Leopard, although supporting PPC is slowing it down? Maybe, then, downgrading to Tiger again might fix things. Mostly, I'm confused at why it would be struggling to play YouTube clips in Safari (and in the newest build of Webkit, even). Any advice would be really helpful!!