What's wrong with this picture?

Just click Ok, and then close the tab. Don't worry your computer is fine. I wouldn't go back to that website though. That is annoying. You have S*** ton of bookmarks! Do you have an ad blocker installed?

 

That would be one hell of a feat to have all that malware on your Mac considering it's showing a Windows filesystem in Firefox for Mac, on your Mac.

 

If you notice, first, that's a Windows Security Alert popup, which has nothing to do with Mac OS X. Second, the files shown as "Detected spyware and adware on your computer" are .exe and .dll files, both of which are Windows-only filetypes and neither of which could run on a Mac. It's completely bogus. It's a fake alert... just a javascript spoof of an alert, designed to get suckers to buy or install their trojan-infested software. It can't possibly harm your Mac.

 

Dont worry about it. I have gotten that too in Safari 4 with Block Pop-ups enabled. Its fake. At least for macs. Its trying to scare you into whatever their selling. Just hit ok and close the tab, and avoid any site that caused the pop up, its annoying.

 

I think the OP was being sarcastic people.