How to align these?
 

How do you align these?

http://img204.imageshack.us/my.php?image=howtocd9.jpg

I'm using fixed width at 760.

Have you tried playing with the width in Style Manager > find your style > StyleVars > Message Area Width (pixels)? I think perhaps the Tags area and Post Icons area are set by percent (take a look in your page source) and the message width is set by pixels, so try changing that.

All I see is:
And:

OK, but did you look at your StyleVars to change the width of the message area? It's the message area that is out of whack.

I changed it from 540px to 515px, and it aligns in Firefox, but it's still off in IE.

I can't help you with IE issues since I don't have IE. You can google IE and CSS and see all the issues it has and the weird things you have to do to accommodate it.

What exactly is the issue with it?

Safari and Chrome will be about +5px from what it looks like in FF. IE7 will be around -25px from what it looks like in FF. It's probably just the way different browsers render the text box. There may not be any css solution, but if you wanted to you could make conditional statements so the width would change based on the browser the user was using and then you would just have to match everything up.