MIME::Lite is good, or their is the MIME duct-tape package: MIME::Tools. Depending on what we are doing we may use MIME::Tools to build the multi-part MIME entity and then use Net::SMTP or Net::SMTP_auth to actually handle the sending part, unless we are using the local sendmail on a *nix box.
Thanks. I didn't even think of using "Mime" in the CPAN search box.
The remainder of your suggestion is very helpful too, since I forgot to mention that this is going to be done on a MS-Windows box, hopefully of recent vintage.