(There is another method, CSS, Click here for CSS Vs Tables).
A debate that rages on and on is how to layout your page.
For those who don't understand the difference here is a quick explanation:
Fixed table width is one where the width of the table is specified in pixels. For example, the following HTML snippet will most likely produce a table that is 500 pixels wide...
<table width="500">
I say most likely because other things can cause the browser to display the table at a different width, for example, if you were to put an image in the table that is wider what you specify here.
A relative table width is specified as a percentage of the width of the visitor's viewing window. Hence the following snippet will most likely produce a table that occupies 50 percent of the screen:
<table width="50%">
The Reason for relative table widths
The biggest argument is that a site which uses relative widths will usually make the page work regardless of the screen resolution of the visitor. For example if you specify a 100% width table it will always enlarge to the maximum size of the visitors screen. This way of desiring your site still isn't full proof. If your images are say 700 wide then the lowest percentage you can go will still depend on the highest width image.
The reason for fixed table widths
If you were to create a fixed width table, that table will retain its proportion regardless of the visitor's screen resolution. Of course if the resolution drops below the fixed width you assigned, the visitor would have to scroll horizontally. But at least your page still appears as you planned. I try to use fixed width as little as I can but there are always occasions where I need to comply with the clients wishes. Forcing something to be fixed will cause problems on different browsers and resolutions so you need to really understand how you can limit the damage it will cause. I will post more about this at a later date.
So what's the solution?
Simply put there isn't one. As long as screen resolutions continue to be as varied as they are now no single solution will satisfy everyone.
Generally speaking if you want greater control over how your site looks then fixed tables might be the route for you. You must bear in mind though that if someone comes along with a lower resolution that your width it will cause them problems.
When you look in Newsgroups etc you will see people say you must use a way over another. Don't listen to them and make up your own mind. What you do need to do for both methods is test it in various resolutions and browsers.
Also see CSS Vs Tables design.