Well aka you will get a torrent of advice re this mate and it depends on whetther you want on for free or paid for.
Personally I get paid for because when all is said and done you get what you pay for!!
I use Kaspersky Internet Security (KIS) 2013 and Malwarebytes (MBAM) - free add on and SuperAntiSpyware (SAS) - free add on myself.
If you want my advice I would include the CClenarer app (free) for tidying up your machine and keeping it clutter free. Kaspersky Lab US | Antivirus Computer Security
< be very careful where you get it from it is regional ie buy it here in Australia and it will not activate in the UK. If you want this one I cn guide you with a great configuration set up. Malwarebytes : Free anti-malware download SUPERAntiSpyware | Remove Malware | Remove Spyware - AntiMalware, AntiSpyware, AntiAdware!
< download the free version CCleaner - PC Optimization and Cleaning - Free Download
< download from piriform
There will be more to come I expect and have your head spinning LOL!!