>>With the Mime, you _can_ have both: just lead with the Text version so that the text
>>clients can read it. You saw the mail I forwarded...
>Sorry, I'm being thick headed. I didn't see it in a mail client, and I guess I didn't
>read it carefully enough...
>
>An HTML capable client will ignore the "Content type: text/plain" section? And vice-versa?

Yes. However, I don't know the exact syntax required to produce that effect. This might help:

http://dsv.su.se/jpalme/ietf/web-email.html