change site width? whats the benfit?

How do i Change my website width, I want it to take up the whole browser, Now if i do that will i experience any error later on or image conflict? Thank you.

I could be wrong, but if you design the site with your monitor as a guide, and you happen to have a bigger than average monitor, then all those old fashioned folks with smaller monitors will be seeing something very different than you.

This is why most websites of any value have kept to an approx, 750 pixel content width.

See Amazon, Yahoo, MSN, ... Then see what happens when you shrink the window down to what a 15" monitor would look like. Usually you can do that without having to scroll laterally.

It's totally a matter of preference. If you don't care, then spread yourself out.

You can design a site for fluid width, meaning that it expands and contracts based on the user's monitor (Zin's reference to Amazon etc.)

The basic way to do this is to look in your /includes/templates/your_template/css/stylesheet.css for #mainWrapper and change
width: xxxpx;
to
width: 100%; (or 97%, 90%, etc.)

Depending on your template, you may need to make other adjustments to get it to look good when changed. Some templates are designed for fixed width only, and are very difficult to make fluid.

The days of planning for the 800x600 monitor are gone by the wayside.
That said, most folks back away from spreading Zen-Cart across the page because of it's tendency to mess with the header and nav graphics.
A simple fix is to incorporate the sales text into a header graphic, center that graphic in the header, and background color the header to match the graphic.
It's probably a good idea to keep the header graphic under 800 px wide just in case.
Personal pet peeve -- Zen Cart's css is set up where most of the text (p tags) inherit a text-align: center from previous text. This can really mess with the readability of the text. Long ago, I set the p tags to text-align: justify. This addition to a "spread-out" or fluid Zen-Cart will look better to the customer in both readability and the way the text moves as the browser window is adjusted.