Looks good in Firefox, but there's a few misaligned graphics in IE6. I know you guys are Firefox fanatics, though you should keep in mind that Firefox has only about 15% of the market share, while IE6 is around 75 - 80%.
I've dabbled in forum skinning, and always made sure it looked right in FF and IE, otherwise it just looks unprofessional when viewed with broken or misaligned graphics, particularly for a skinning forum. I also never use transparent .pngs, simply because IE6 doesn't support it, though there's a hack you can apply that uses DirectX to display PNGs properly in IE6, but it has to be applied on the server end. Though I do see your using .gifs for your transparencies, which is perfect for IE.
