I am running Ubuntu 9.10 am not sure if its in 9.04. But try this in
terminal mode/comand prompt :- type 'locate software-center' and see if
the program is listed (ignore quotes). If it does not show its not
installed on your machine and or not part of 9.04.

If not there then I think its very worth while installing and the best
way probably is to visit its web site (try a google search).

I have spent some time looking thru the programs it lists and it has
become one of my must haves.