"Centered" portals have always looked weird to me
I'm no expert on user interface design, but I've always found strange those sites that try and adopt the potal mentality - being a single repository for a lot of information - when they center a fixed-width HTML table in a page. The resultant gutters of empty space on either side, white or not, had always rubbed me wrong.
I'm of the school that typically uses a <TABLE> that's 800 pixels wide, and left justified. People running monitors with large resolutions will get a bit of nothingness on the right - but only on the right. The content-sitting-in-the-middle-of-nothing approach just never grew on me. Especially for portals.