Ok. First off. An ATA drive will slow down to any speed necessary, for instance an ATA-133 drive will work on an ATA-100, 66 or even 33 bus, you just wont get anything over 127gb on certain ATA buses (i forget which). As for two drives on one ribbon. Until recently the powermacs only had one easy option for an extra hdd, and this necessitated the use of both ribbon terminals. this is a common thing, and is no problem at all. and for those PM that did come with a second controller, it was only ATA-66 if i remember correctly.