[BenjArriola]

Considering your case E-senses, I would use some type of algorithmic redirect instead of mapping out each old URL you find indexed or has a backlink.

Depending on the server-side language you have, the code will be different. Since I am more of a PHP guy, for your situation having this:

old url: www[dot]mysite[dot]/products/item3
new url: www[dot]mysite[dot]/products/a435

That would simply be something like:

<?php
  if(str_pos($_SERVER[REQUEST_URI],"/products/") === 0){
    $productCode = explode("/",$_SERVER[REQUEST_URI]);

    // Create a database of all old URLs and new URLs
    // if that does not exist yet. If it can be drawn from 
    // the same database, then good.
    // Input the old code in $productCode[2]
    // And spit out the new one and assign to a variable like
    // $newProductCode

    header("HTTP/1.1 301 Moved Permanently");
    header("Location: http://www.mysite.com/products/".$newProductCode);
    exit();
  }
?>

If you are using some other language, there should be some counterpart to this. If you are not a programmer by heart and has a hard time interpreting this. Find someone that can do this for you. If you have all old URLs in some archived format, text file, csv, Excel, or even the old site exist as saved static pages, I am sure there is a way to extract all of the old information and map it out to the new one and create smart 301 redirects so you can already forget about it once it's done.

Originally Posted by E-Senses

Thanks so much for your reply OWG!

Just one last thing to confirm that we will be doing things right. I just want to make sure that your answer is vaild in the scenario in which the domain is still the same. So the hosting will be different, but the domain it will be still the same.

Example:
old url: www[dot]mysite[dot]/products/item3
new url: www[dot]mysite[dot]/products/a435

If it is valid your answer in this scenario, then would you mind explaining why googlebot would still inisist on accessing the old hosting when the domain is pointing to the new hosting?

Again thank you very much for your answer!