Your habits are very secury. Congratulations. 
But, there are some ‘leak’ points that the resident protection could solve:
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The preview panel of Outlook Express, for instance, can allow trojans to be installed. You do not need to ‘open’ the email, just preview it.
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When downloading, after saving a file could be so late (for non archive files, for instance, .exe .com)
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If you are receiving virus from email, why do you want to disable the Internet Mail provider?