How to handle 6000 bad links? - OSC to Zen Conversion Project Ready to Go

After a couple of months of work, I'm now about ready to retire my OSCommerce site and move everything to ZenCart.

I still have a couple of concerns and the first is with the search engines. The site has been around for several years and enjoys good placement with Google and others. But once I change to Zencart, none of the current product and category links will work.

I'm not really concerned about customers being able to find things, once they are on the site they can find what they're looking for, but I don't want to lose my search engine rankings or even be dropped completely.

What is the best way to handle this?

Should I just have a custom 404 page to catch everything?

Is there a redirect that I should put in an htaccess file that the search engines would prefer?

Would it be possible or even wise to have some kind of url rewrite.
The old links are similar to the new ones, typical url's might look like this in the old system:
/product_info.php?cPath=31_134&products_id=6534

The same link would look like this in ZenCart:
/index.php?main_page=product_info&cPath=31_134&products_id=6534

There are some variations on this, so not sure if something like this would work, or if it would be a good strategy.
Translating links forever probably isn't a good thing to do.

In addition, I will continue the daily upload of all of my product info to
Froogle and XML site maps to various search engines.

Any help, comments or insight would be appreciated.

thanks,

Ed

Try a search of this forum for 301 redirect author-mprough - there should be several posts that will help.

See if this thread helps Forwarding from old shop to new http://www.zen-cart.com/forum/showthread.php?t=112539