Tidbits -- Centering Unknown Width and/or Height elements:

Sample Html+CSS that work in IE 6 and Firefox

It is easy to center stuff whose dimensions are specified using width and height.

And it is easy to center anything, by wrapping it in a <table>.

But it is not easy, using only CSS, to center an element whose dimensions are NOT SPECIFIED.

For example, the contents could be inserted dynamically from a database, so you don't know a reasonable size.

Or perhaps you are designing a Template, and you want your customers to be able to type in content later, without concern for the size of the content.

Anyway, here are some sample pages, showing both CSS and Table-based solutions.