Outlook already allows you to convert your contacts into vCard format (vcs file). However, you can only convert one contact at a time. Plus, Outlook can only read the first entry of a vcard file no matter how many contacts are contained in that file.
Now however, you easily convert all your contacts to vCard format with one click of your mouse with the VCard Converter Add-In. It allows you to export all your contacts within a folder, or you can choose to export just the ones you select. In addition, you can import multiple contacts from a single vcf file.