Hi dixielady627g,
You should be able to play Riddle of the Sphinx on Vista, but if you have any issues you can always run it in XP Compatibility mode. If you need any help changing those settings, you can see the following help pages article that offers some step by step instructions.
Game Display Issues with Vista
If those steps seem unfamiliar though and you do experience some issues, you can always write into our Customer Support team by clicking on the green envelope on the right side of this page. They'll always be more than happy to help and offer some different steps or even figure out other issues that would be there.
Cheers!
bfgEuphrates
Edited on 08/14/2009 at 11:15:18 AM PST