In Europe (according to these stats at least) Firefox has just caught up with IE at 39% each (though personally I feel including the 3% still on IE6 is cheating in their favour).
Generally I feel the not-IE percentage is a much more important figure than how the rest breaks down and it would appear from this stat source that Chrome is stealing more from IE than from Firefox, so it's all good.
http://gs.statcounter.com/#browser-eu-monthly-200912-201011
And IE fell below 50% globally a few months ago.
http://gs.statcounter.com/#browser-ww-monthly-200912-201011
Generally I feel the not-IE percentage is a much more important figure than how the rest breaks down and it would appear from this stat source that Chrome is stealing more from IE than from Firefox, so it's all good.