free? norton 360 trial. it lasts 90 days, so every 90 days you pull a new version and uninstall the current, install the new.
it's just liek the paid $80 version. but you need ot constantly reinstall it due to the trial limitation.
Norton is easily the best security (not just AV) software out there.
in the past i have used the following problems all of them failed at some point resulting in losing irreplaceable data, and days lost in system recovery.
MSE (microsoft security essentials)
i tried norton out exactly in that form, and after a year of absolutely no problem I decided to buy the software. i've been using norton on my desktop since, absolutely no problems, it tells me if something tried ot hack me to it found a trojan or whatever.
since two years ago when AVG & malwarebytes totally failed and it resulted in loss of my netbook (it's a total loss since win 7 starter does not have a recovery disc) I put norton on my laptop too.
my work computer is most recent to get norton, after a virus wiped it out a few months ago. despite MSE and eset AV.