If you set up your categories as described in this post, then any categories that are at the same level as "Products", ie. direct descendants of the default category, should not show up in the top navigation.
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<apache>
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<drupal5>
<drupal6>
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<foo>
[foo]
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If you set up your categories as described in this post, then any categories that are at the same level as "Products", ie. direct descendants of the default category, should not show up in the top navigation.