Per the newewst HTML documentation, the <center> tag is obselete. Instead, use
<div align="center"> and </div>.
To prevent messy line breaks and such, I'd reccomend declaring a table with a
predefined width (say, 700-800 pixels) that most monitors would be able to fit. Then
you can work with that and not have to worry about how it will look. Sure, there will
be some white space, but the page will look nicer and more compact.