force index.php to always show category 21

[djalias]

basically i want index.php to always show all the items of category 21 on the front page instead of the "new products" bit.

 

the url for this is

 

www.sitename.com/index.php?cPath=21

 

but i do not want to do it with a redirect of some sort, i want it to be coded into index.php, or application_top, or whatever the appropriate file is that decides what category to show you.

 

any ideas or pointers?