[SOLVED] Centering Issues

Hi there

One more issue that is driving me up the wall, and is probably just me doing something wrong.

Site is artcurvedstraight.org/home

Basically, I have a centered header image and page menu. For some reason, centered page content shows up too far to the left. So, for example, my centered slideshow appears off to the left and I can't figure out why. Is it an issue to do with Center Column width for example? or Center column padding?
I'm stumped.

And, excited to get this resolved, since once I solve this and my previous post (just posted) I'm done with this site.

Thanks for your assistance and continued support.

Cheers
Josh