word 2007 only can insert either picture (logo) or text.
That's true if you insist on using the Watermark command for both. But...
A "watermark" is really just a picture or WordArt object anchored in the header
and suitably faded. You can insert your own picture or WordArt -- as many
objects as you care to use -- and they'll all happily coexist. The problem
you're having is because the Watermark command removes an existing watermark
before inserting a new one, so you can only use that command for the first one.
See
http://sbarnhill.mvps.org/WordFAQs/AnchorToHeader.htm for an explanation of
anchoring things in the header but placing them outside the header area.