Banshee032:
I don't know if that is the same thing as what they are reffering to as rewriting URL's but I am optimizing my products by adding meta tags....it says it improves google search if the google robots can read your meta tags....to summarize it sorry if this doesn't make sense I'm pressed for time
Google cannot and does not "read URL's". The URL is simply a doorway to your content, and as long as google can "get into" that doorway, and the page it finds makes logical sense, with good internal link hierarchy, etc, the dynamic nature of the URL is just fine. There is no "SEO advantage" to changing the URL... In fact, these modules can actually put your site AT RISK.
Back in 2006, MATT CUTTS (head of Google Search Quality Team) went onto his blog telling people that it was NOT NECESSARY to re-write URL's, if the dynamic URL was well-designed.
And in Zencart's case, the dynamic URL's are VERY WELL DESIGNED and Google has not the slightest problem finding, navigating and indexing them.
Go to Google now, and search for:
refurbished domestic heating spares
The following site should be seen several times in the top ten results: igniteheatingspares . co . uk
That site - built by my colleague, schoolboy (and a bit by me!) gets to the top of Google on practically all of its key search terms and it does not use these dumb SEO URL modules.
Stop fretting about the URLS. Leave them alone, and focus on CONTENT in your website.