I am a website designer. A client has referred a website to me having
a "style" he would like me to emulate. From an esthetic standpoint
(graphical layout, menu navigation), how close can I get to what is
shown on any given site without infringing on the original site
owner's rights? My client runs an engineering firm, and the original
site is an architectural firm (   http://www.bellarc.com   ).

The original author used Macromedia dreamweaver to make the site:

From the source: "function MM_findObj" that MM_ gives it away. This
means you can essentially copy the site exactly as it was generated by
an third party, openly availible tool and not an author.

cheers,

catch

My lay understanding of copyright law in your situation is as follows:

Color schemes, choices of font, placement of items, and other thematic
elements are not protected under copyright.  Writing and images are
really the only things that are protected.  So long as you don't copy
the other site's presentation so closely that one might be fooled into
thinking they are actually at the other site, you're fine.

Even if a site is generated by a software product, the output (HTML)
is still protected by copyright.  Keep in mind it is the actual HTML
that is protected, not the layout it produces.  Consequently, you'll
need to recreate the thematic elements you want to emulate since
copying the HTML verbatim and substituting your own text and images
could be considered copyright infringement.