It all depends on the user with anti-virus software. One software may work for one person while the other may not work for you. I don't run any on the desktop since it's mostly for gaming. Avira is crap and if you want to uninstall you have to use safe mode and their remover. I used to use Avira, but not after I had trouble. I tried almost every single anti-virus there is and I'm happy with Bitdefender Free. Like Panda Cloud it's cloud based. I had problems with Panda cloud though. My netbook uses Clamwin, I had tried Clamwin on my Win 7 laptop and it wasn't working right, but it works in XP alright.
On my laptop I use Sanboxie for the browser, have Comodo Firewall installed and Bitdefender free.
The scanners I use are: Herdprotect, Malwarebytes, Sophos Virus Removal Tool, SUPERAntiSpyware Free Edition, Adwcleaner and TDsskiller. If you have malware run Rkill first.