I dropped of some files to be printed at a photo place (I'm in the process of finding a printer that works well with my color profile) and was surprised when they asked me if I had scanned the files with an anti virus. I am an OSX user- I don't dual boot. So my need for an AV is minimal. The printer, on the other hand, feels that even though the files may not effect my MBP, they might contain residual viruses that are dormant on my system. They feel that the files need to be scanned prior to drop off so that their work flow doesn't get corrupted. Now I understand that they get a zillion files a day from the public. And I doubt I'll use these guys at all, since I don't like how they handle files before printing. But it seems there might be a point there. Do Mac and 'nix users that share files with others need to worry about being carriers of viruses and various 'warez? If so, to what degree should we worry about it? Does it serve the windows user right for not seeing the light, or not securing their system? or should I start running an AV just to be nice and not infect others? If so, which one? is there an open source option? Norton? Avast?