jQuery browser - IF Firefox2

jQuery browser - IF Firefox2

Hello everyone! I'm using jquery.corner plugin to make some cool round corners for my website.
As I need different corner colors in each corner of my divs I have to make seperate code for Firefox3 / Chrome and seperate code for the rest of the browsers. I already have IE / Opera code but I also need to address Firefox2.

How can I use the jquery.browser function to address firefox2?

I'm using if (!$.browser.opera) to display the code that should not be seen by Opera. I want to add firefox2 to this "if equation".

Please help :)
Thanks in advance!