Which Anti Virus your used.

I'm personally a Norton fanboy (shut up!) but as much as it pains me to say it, BitDefender is winning the current round of AV lineups. :(

Bitdefender Antivirus

Bitdefender

microsoft security essentials, free and wont bother you like others.

Kaspersky

Switched from Avast to Avira. Amongst the free ones, Avira has been scoring highest in AV benchmarks. For the paid ones, Kaspersky is #1 but I don't quite feel like paying up (yet?)

ESET Smart Security 6 works well for me. It usually goes on sale at least once a year and you can get a license for like $10.

Eset Smart Security

avast

I was using avast free but just before xmas they offer me the pro on a xmas special for £9.99
so I had that as seem a good deal