There are basically two types of primary navigational layouts. Those that use the horizontal menu bars and those that use the vertical menu bars. There are a few rules to guide you when deciding which menu layout to choose form.
In general, if your primary navigation contains few items such as the example items listed above then the horizontal menu bar makes a good choice to consider. If your menu item contains several categories as is common with E-commerce websites then a vertical menu bar layout may be suited for your website.
Ideally keep vertical menu bars placed on the left of the page unless you are serving up a page with a right-to-left reading language such as Arabic.
These rules are more of hints. The important think to remember when planning your content is to try and get the best generally logical groupings that can suit a place on the primary menu bar. If your primary navigation contains too much stuff then it could also be a hint that your content is not organized well enough.