AV and anti-spyware software really isn't necessary on OS X, as there's damn all out there for them to find (except Windows malware, which won't affect OS X anyhow).
If you really MUST have AV, then try ClamXAV, which will, at least, prevent you from wasting your money.
Forget anti-spyware, though - there just isn't any at present.
Note: none of the above applies if you are running Windows on your Mac - via either bootcamp or VMWare/Parallels. In that case you will need to install regular Windows AV and anti-spyware applications - but only within Windows itself. I recommend AVG free and AdAware.