As Pete said Malwarebytes has an excellent reputation.
There's a list of free Antivirus software here
http://www.techradar.com/news/software/ ... ed-1057786
And a list of (mostly) paid ones here.
http://www.techradar.com/news/software/ ... ed-1057786
Personally I choose to pay for Bitdefender because its rock solid and doesn't slow down my machine and it works out at a few pence a day but plenty of people don't pay and get good products.
Another bit of software (free) I would definitely recommend is CCleaner by Piriform.
https://www.piriform.com/ccleaner/download
It will clear out your search histories, delete caches and so on more thoroughly than you browser. It will also clean up your registry. It gets rid of a lot of stuff that you don't need on your pc but isn't hostile, broken links all sorts. I use it every week or so just to keep the pc running as efficiently as possible.
I also use an add on called Disconnect on Chrome.
@ Graduate Owner, I found this post:
"I also have these AdChoice ad's which infected my browser Firefox. I updated everything possible, installed several Malware Removal programs and they did not find any of these AdChoice.
After wasting a full day looking for an answer, it turns out that it was added by my Internet provider. Don't know if I am allowed to say their name, but by clicking on the AdChoice little arrow on the corner of the ad, it takes you to a page that lets you opt out of these ads. So, with all of the time that I have spent searching for a fix, turns out the answer was under my nose. Hope that this will help everyone with these pesky ad's. This page also told me that it does not have anything to do with my searching for a product online, this is bull also. Last Monday I searched for a new laptop for my daughter and shortly after, I had ads for laptops all over my providers homepage. WTS I plan to let my Internet provider know how I feel about this."
Here
http://www.tomsguide.com/answers/id-234 ... opups.html
Hope it helps.
Cheers Chris
