However I use Windows defender for my windows 8 Pc and Microsoft Security Essential for my Windows 7 Pc. Haven't faced any problem till today. Might be the reason that i never visit bullshit sites or download any bullshit contents. But these both free antivirus are great for my PCs.
Panda Software (internet security) is the best hands down... Norton and Mac-A-Fee both are border line tools.
Also, if your solution is a free one remember, you get what you pay for!