Getting rid of a virus?

I was browsing the internet for some information on a older TV show and when I clicked the link to the website and this pop up came up. I figured it was asking me to download something so I clicked no and it came back up and I've kept clicking no everytime its popped up. I even got fed up that I restarted my computer twice and it hasnt gone away. Right now I'm running my Web Root with Antivirus and Spy Sweepware hoping that will pick up on the virus and get rid of it, but any recommendations on how I am to get rid of this thing?