Scroll to the bottom of this forum page. Click on Mac under Get Skype. Scroll to the bottom of the resulting page and click on the link to download v2.8.
Versions older than 2.8 are available from oldapps.com.
Thanks this helped have old and new version but when I open the old skype it just defaults to downloading the new version which doesn't work with my macbook 10.4.11???
Same here, tried to upgrade, didn't work, so went back to the old one, only to find that now it won't stay on for more than a minute before forcing me to upgrade to the new version which doesn't work. Get your act together Skype!!!!