I have a laptop that for some reason certain websites don't fill up the screen. Sites like Cox.net, MSN, USAToday, etc. I have a white bar on both sides. Any thoughts?

Probably the way the sites were authored. Some sites want to maintain a certain look.

You can "hard-code" the size of a web page to be a certain height and width. Some sites do this to fit into an AOL window which has a specific configuration that makes it look like AOL content.

Im sure there are other options but using Firefox will alleviate this issue as well.