use firefox or chrome web browsers. make sure you install the Adblock add on. If you are concerned about blocking a site's revenue, simply add it to your white list and enable the "allow non intrusive ads" option (its enabled by default).
adblock stops all that fake download button crap and prevents accidental clicks. firefox and chrome both have great security features built in so you really have to TRY to get a virus.
Also, i use either AVG, Avast, or microsoft security essentials as my antivirus. they are great free antivirus programs. i see no reason to pay for a subscription to an antivirus provider when theres great free alternatives.
you can use malwarebytes antimalware to do a scan for viruses and stuff. it catches a lot of different things.
if you have a search redirect problem (IE you go to google and it bounces you to some random non-google search engine or redirects you a bunch of times first) you can get rid of that too.
you can grab the file called "tdsskiller"
http://www.bleepingcomputer.com/download/tdsskiller/
its free, works great. but make sure you thoroughly read the instructions and disable antivirus for it to run. this is what you run when you are 1 step away from nuking.
Personally, i am of the opinion that once you have a virus, your computer is permanently compromised. i nuke immediately. I always have backups of all software and all data on hand.
Important stuff sits in someplace other than My Documents (like a seperate internal hard drive) and gets synced to something like dropbox or crashplan (or both). music, video, photos get moved to a NAS. photos get synced to crashplan. movies and music i dont really care if i lose. best backup method in terms of price/gb is getting single hard drives and a hard drive mount.
i can grab a 3-4TB hard drive, pop it into the mount, and make a full backup. Then i repackage the drive, label it thoroughly, and keep it away somewhere safe.