Does anyone here actually use antivirus for their MacBook Air? I know at the Apple store the sales reps are taught to say "macs don't need antivirus", but is that really true? I figure that the low marketshare (compared to PCs) is the main reason people say there isn't much motivation for hackers to write Mac exploits but given the rising popularity of the platform and growing user base I would assume that there are more and more instances of Mac exploits either here or on the way? If you do use antivirus, please say which one and if it negatively affects your Macbook Airs performance or battery life. Thank you.