Well if you are only going on the habit of browsing to forums and watching videos on known providers like Youtube, Vimeo plugging USB and others then WD is fine as considered to be Baseline protection.
Almost all antivirus companies offer Offline Installers and Offline Signature/VirusDatebase updates that can be downloaded elsewhere and then transferred to the offline system including Avira,Avast,Qihoo 360,BitDefender Internet Security
Qihoo 360 antivirus doesnt have BitDefender and Avira engines enabled by default, so u should enable them manually in settings menu.
Original BitDefender internet security protection is better then Qihoo 360 with BitDefender Engine enabled, but Qihoo is free and doesnt req online registration. German Avira Antivirus also offers free version with offline installer