Static URLs are known to be better than Dynamic URLs because of a number of reasons
1. Static URLs typically Rank better in Search Engines.
2. Search Engines are known to index the content of dynamic pages a lot slower compared to static pages.
3. Static URLs are always more friendlier looking to the End Users.

Example of a dynamic URL
http://www.widgets.com/product.php?categoryid=1&productid=10

This tool helps you convert dynamic URLs into static looking html URLs.

Example of the above dynamic URL Re-written using this tool
http://www.widgets.com/product-categoryid-1-productid-10.htm