I came across this website called "I Am Second" where some relatively famous (well in America they are) Christians give their testimony. The Brian Welch video (ex-guitarist from Korn) is the most popular and in some ways it was a very high profile conversion.
Give it a watch and see just what a difference Jesus can have on a person's life. To me hearing his story and seeing the beautifully extreme transformation is just astounding.
Watch the video here: Brian Welch - I Am Second
(Warning - He talk a bit explicitly about his previous drug use, in some ways that helps show just how radical the turnaround is)