All adware/spyware etc dont necessarily just come from porn sites they can come from absolutly anywhere on the internet!!

About a year and a half ago i remember a patch for Operation Flashpoint from Codemasters had a virus in it!

You wouldnt expect to get a virus downloading a patch for a game from a very reputable company!

But hey, it happens!

All you can do is install a firewall, anti-virus and things like spybot and keep them updated ensuring you use them regularly and be very paranoid about everything!