Which Anti Virus your used.

Bitdefender

MS Security Essentials does the job for me! + It's free :)

Microsoft Security Essentials. Seems to work good and doesnèt take up a lot of resources

Bitdefender

f-secure client security

I use AVG but to be honest it's too intrusive and gives me tons of false positives. Foes anyone recommend a better antivirus? I read that the time between a PC getting connected and the first virus/hack is in a matter of seconds...

avast

Eset x64, no issues so far and doesn't bog my system down.

I use Avira it's a free version. Been doing great with it so far!

I've used NOD32 and Bitdefender. They're both lightweight and effective.