CSS Fixes for Internet Explorer

I have a website that looks fabulous in Firefox but it looks funky in all versions of IE, even IE 9. In IE, the entire site is jammed to the left of the screen (when it should be centered), the footer floats all over the place when it should always be at the bottom of the site, and on the homepage for some reason a table cell is pushed very far down the screen rather than being nestled next to another cell like it should be. I've had a friend who is good with CSS take a look at it and he can't figure out why it looks this way in IE. This should be a fairly quick fix for anyone who is very proficient with CSS.