Will FaceTime work on my Mac?
will FaceTime work on my Mac OS X - Version 10.5.8?
You have to upgrade to Mac OS X Snow Leopard (Mac OS X 10.6) to get FaceTime.
First, see if your computer is supported > http://support.apple.com/kb/sp575 If it's compatible, buy Snow Leopard. Then, make a backup of your data, insert the DVD and upgrade to Snow Leopard.
The disc will install Mac OS X 10.6.3, so open > Software Update to install Mac OS X 10.6.8. After updating, open App Store and purchase FaceTime