Browser Compatibility Problems

Hey there…I just switched from MT to Word Press and love it so far. When I made some style adjustments I did so with FireFox. I generally build it FireFox and then see hwo it looks in IE to make some minor adjustments. This time around I redesigned it and it looks fantastic in FireFox when I looked at it in IE it was totally messed up. I am used to there being a few things to adjust here and there but I don’t even know where to start with this. Is there anything huge I messed up that could cause such a difference between the two browsers? I woul appreciate any tips on where to start or what to do to get these to match up. Site below…thanks!

http://www.zachishere.com/wordpress/