google unwanted pop ups

I have customised igoogle set as my home page on safari. over the past few days whenever i open the browser and the google page appears, a pop-up window appears with a link to GTopstats.com which looks like one of those dodgy annoying websites with all kinds of links to things not necessarily community minded.
I tried in firefox and a pop up was prevented by the inbuilt blocker so i suppose it something to do with my page and not browser specific.

i don't know where this is coming from and i am worried that maybe it is some kind of spam or virus or phishing thing. I do not really experience pop ups from my google homepage and I would have thought that google may have prevented things like this happening or has this somehow been hijacked?

is it possible that it is coming from some of the gadgets installed? its very annoying and i feel i have been infiltrated!

Thanks
RE

Under Safari in the Menu Bar make sure that Block Pop-Up Windows is checked. Download and Install Glimmer Blocker.

OK, done.

Is OSX susceptible to virus or hacks or any other nasties from these kind of pop ups?