I had a Mac G5 Tower purchased in Jan 2004 that had a SATA hard drive installed and an expansion bay in which I installed a second SATA drive. After the G5 main board failed I put the drives in external enclosures and use them via firewire for backup and cloning. If you do not want to mess with enclosures then there is an alternative solution at Granite Digital.

http://www.granitedigital.com/usb20tosataideharddrivebridgeadapter.aspx

I have one of these setups and can access any bare SATA or IDE (ATA) hard drive without any problem.

http://www.granitedigital.com/images/usb-sk.jpg

What is new is not necessarily needed and what is old is not automatically obsolete