Answers: Here is a great relationship that will allow you to come to your own conclusion.
I one-sidedly do not use anti-virus software, but am aware of the risks involved if I encounter one. Always hold a backup.
Good Luck
Chadwick
In a word, No. Mac OSX is extremely immobilize, and as far as I know, within hold singular EVER be 5 virus for Apple Macs, as anti 1000000's for window base machines.
(The first ever be discovered surrounded by 2006).
I hold be running on OSX 10.4 since March, and havn't have a problem. I also know that if you ask contained by an Apple Store, the entire staff will explain to you they don't own antivirus.
A tip though: Make backup.
You are far more possible next to OSX to lose your information due to a broken Hard-Disk or similar. If you copy your prominent stuff to another frozen disk or to some DVDs every immediately and later, your notes will be restorable!