Ah the wonderful "Do I need antivirus".
Simply put. Yes you do, because one day, there WILL be a virus for linux (infact there already is but they don't appear to spread and the damage they can cause it limited.
If a virus were to infect your user account for example, it may not be able to break you system or mess with your software, but that doesn't mean it wouldn't have access to your /home/ and that is generally where you have what you'd call "important" things