Wow, what a nice debate. A little back and forth, and no name calling. Nice. I've got a few points to consider.
1. tables vs css layout.
Just to remind everyone, based on W3C specs, table based design is perfectly valid html. Yup. Go look it up. Even displaying images in a table. EGAD! You mean that old hack is allowed? YUPPERS. Table layout has not be depreciated. It is permitted in HTML 4.01 Strict, XHTML 1.0 Strict, and XHTML 1.1. There is a Tables Modules in XHTML 2.0 that allows complex content in the cells.
And finally,
the W3C itself says
While not specifically mentioning layout, "to arrange data" fits the bill.
2. Google, Yahoo, and MSN have all gone on record saying that their bots are perfectly able to discern text and images from code. Yahoo and MSN are not as good as Google at separating content from code, hence css based layout, standards compliant code is better for ranking on those SE's. But Google just don't care. They really don't. They said that they can't place a benefit of valid code above valid content. However, if the code is so invalid that the content CANNOT be spidered, then your SOL. So don't put content blocks inside of Javascript, or images (duh) or create a javascript navigation with no href's in it. Google does crawl javascript.
Or programming engineers. If you want an asp.net, php, or cgi coded website to do certain things, and you hire the best programmer to do it, he or she will program the site to function as specified, and as efficiently as possible. (A good coder anyway) The best programming code does not always put out perfectly valid code. In fact, more often than not, it doesn't even come close.
I looked up some of the highest rated websites of their kind, CMS systems that cost hundreds of thousands of dinero, sites that we can all agree that are some of the most trafficked in the world, like cnn.com, bbc.co.uk, time.com, yahoo.com, and just to check a second stringer, lifehack.com. Guess what, they ALL FAILED VALIDATION.
Are you telling me that the people who run those sites are lazy and ignorant? Are you telling me that the thousands of hours of coding where done by lazy ignoramuses?
Maybe, but darn your a prude. LOL
I personally know of no e-commerce or lead generation site owner that is unhappy with "valid enough" code. They want a site that functions, looks good in all browsers, and converts a sale or gets a lead. A site that validates enough to supply this is the ticket. As far as most site customers are concerned, there is no leaky faucet.
Prof, don't ignore SEO. If you design with SEO in mind, you'll see great returns.
I agree with a previous poster on the design of the current site. A graphic designer will do wonders for this site. It's not converting to well because you have better visual marketing on the competition.