How to convert URL's to Links in User posted text in forms ?

Hi, I am trying to display as links the url's posted in the forms <textarea> at my site valueads_dot_biz I am removing all codes and special chars when they post to avoid any injection but when i retrive back form the database and display I want to find the url's in the text and display as clickable links. I found many examples in the php manual and on the web.. but still having hiccups I'd like some suggestions form you people. Regards Hemanth Bangalore, India