Nod32 is the best around and uses very little CPU power so wont make the PC slower than a lada

but its not free , i know it used to be possible to get codes but a certain web page / forum has no closed so no more codes

i am now using avira antvir personal edition classic which is free and seems quite good , only problem i have found is when it scans , if it find anything it pauses the scan but doesn't alert you to anything