The other obvious place for a navigation menu is at the upper left side of the page.
If you decide to use a side-menu you need to divide your page according to it. How much space should be used for the menu?
First off it is recommended to allow the content-part of the page to carry industry standard banners at size 468x60 pixels.
This leaves you with an option to have a menu that is up to 620-468 = 152 pixels wide. If the banner should be allowed a 1-pixel border (which is often required) you're left with a menu at maximum 150 pixels width.
Now with a 150 pixel maximum width for the menu
graphic objects at 468x60 and 234x60 becomes irrelevant. They don't fit in the menu no matter what.
Unless we accept to be limited to have only
Micro Buttons in the menu we can conclude that the menu must be at least 120 pixels wide (in order to allow the majority of graphic standard-objects to fit).
The gap is thus between 120 pixels and 150 pixels.
When designing for 620 pixel width of the entire page there really aren't any restrictions to what you decide, as long as the menu is kept between 120 and 150 pixels.
However, as we shall see in the next section, 150 pixels is a genius decision when you decide for 800x600 pixel screens.
The final word to say on fixed design for 620 pixel width is that it actually is impossible to have a menu on each side of the content - if the design is made with respect to industry banner sizes.
You might add here, that you don't want banners on your page anyway, so what's the problem?
The focus on the industry standards for banners is not limited to banners only. Since so many sites carry banners, and thus are divided according to the standard sizes of them, many other tools reflect the same standards.
Java applets, animated GIF's, web-photo-collections, real video etc et etc very often adopts the same standards.
This means, that if you decide to not take the banner-standards into account you limit your future options for adding both banners and cool effects to your pages.
Of course it is your decision to make - but an advice is, that since there really aren't any other important factors to take into consideration you might as well divide your pages according to the industry key-measurements rather than just pick a size out of the blue.
The final example in this section shows the logical way to divide the screen when designing for a fixed width of 620 pixels:
60 pixel top-banner/menu with a 120-150 pixel side-menu and 470-500 pixel main-content.
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