Can you show us some site statistics? Does she get traffic from her Google AdWords campaigns?
Look at your stats and find out when the site visitor abandons the site - it sounds to me the site is not user friendly and/or doesn't bring the message across to generate leads or sales.
Sure - table less design is great - most of our sites are now table less and also validate - but that's just and added plus and doesn't help much with the SEO side of things. Just with clean code and looking ahead of the coding trend...it doesn't hurt your SEO either
You can always improve on the SEO (yes - Dreamweaver works just fine - but any tool is only as good as the person using it), but her problem seems to be the usability and marketing message itself - I don't think hiring an SEO company at this point will help her to convert visitors into sales unless the SEO also does a site usability and marketing analysis and suggests some redesign...