Salut à tous, malware is not a problem for me, but it can affect mac users.
I did a search for a definition of malware and google came with this:
Malware (for "malicious software"): is programming or files that are developed for the purpose of doing harm. Thus, malware includes computer viruses, worms, and Trojan horses.

Viruses: Mac is not affected by viruses, but some macro virus for microsoft office can affect mac users (I got infected with the melissa virus by exchanging .doc documents between the university and my home computer).
Worms: The Apache server that come with os x is prone to worms that affects, of course Apache (I know there are worms for older versions of Apache targetting Linux users, -but it could be mac users as well depending what the worms is targetting on the computer-).
As for Trojan Horses: Macs aren't immune to them: there are none for now, and writing one for mac is hard as most internet services on os x are disabled by default... but it is possible.

Of course comparing malware for os x and windows is comparing apples to oranges at the level of magnitude of attacks...

For now I fear more antivirus software and badly or old written softwares (not on purpose however -as it is by malware-) on my mac than spywares, malware and the crew.

Bonne fin de semaine

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Liens d'intérêt /Links of interest:
Gnutellaforums en français /The House's rules you have to respect / First search the forum, then create a thread / Free software alternatives! - Logiciels alternatifs gratuits!/