Huge fonts in Firefox/Opera on FC6

[microchip]

Hi,

I'm having an annoying problem here when using both Firefox 2.0 or Opera on FC6. The problem is that those browsers are displaying pretty large fonts and no matter what I do I can't seem to change that. On my openSUSE 10.1 system everything is just fine, but when I switch to FC6, I'm stuck with this annoying problem. I've tried like a thousand times to get it right in the preferences of both Firefox and Opera but I still get those big ugly fonts. As an example I give you a screenshot of Firefox on my openSUSE 10.1 system and one on FC6.
Please help, how can I make it behave/look the same as in openSUSE 10.1?

Thanks

Screenshot on openSUSE 10.1 - the way it should be

Screenshot on FC6 - annoying fonts