Try this for the textarea:
<textarea name="Comments" rows="8" wrap="wrap" style="width: 300px"></textarea>
You're missing the "name" attribute, which I guess will be the problem as the script doesn't know what the textarea is.
This is the only difference i can see from the Wiki, so hope it sorts it for you.
I've lifted it straight from the Dreamhost Wiki entry for Formmail
Edit: rlparker... just saw your message after I posted - can anyone beat you to posting?? From what Laura says, it appears the form did send, but the comments box didn't come through. Is the DH-only delivery still enforced?
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