Transparent Alignment

Continuing on with my last post about transparency, I am currently working on revamping the AnacondaSoftware website, with a new design that will unify the main site, the DevBlog, and the Forum, with integrating the main site as well into PivotX. At the moment in a test server I'm working on the template, which will be similar to the AnacondaSoftware site currently: a blade of information centered down the middle of the page.

At the moment I have begun my layout buttons, and I have also stuck on there a small black square at 50% opacity, to see the translucency for myself. I'm booted into Windows Seven right now, to test it under IE8 Beta, and something different happened: the blade is not centered on the page.

Instead it is off to the left, with everything aligned based on that. Setting IE8 to Compatibiltiy Mode moves it all back into the center where it's supposed to be. I'm implementing this in pure CSS, no javascript, and it loads fine in IE7 and Firefox, so I'm not sure what is going on. IE8 should be improving upon the standards compliency, so am I then using something non-standard to center it?

Oddly enough the AnacondaSoftware site as it is currently has it's centering working just fine, and as I recall that is written in pure CSS as well, so I will have to compare the style sheets between them to try and fix this.