There is a service pack 1 for Win 7. That said, are you keeping the cabinet connected to the Internet? If so, then yes, patch it and keep it patched. Most viruses, etc., are targeted at vulnerabilities that have already been patched and that people unfortunately don't keep up with. If it's an offline PC then it doesn't matter.
What I wouldn't do is put Java or Flash on the box. Skip Acrobat if you can too.
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