Output While Executing

I currently have a script which performs various time-consuming tasks and would like to have a status/progress report output to the browser as the script executes. All I'm looking for is a way to echo out simple messages such as "Task 1 starting", "Task 1 complete", "Task 2 starting" and so on. I have seen this behavior implemented in asp, however when using php it seems that the entire script is executed and then only when complete is it sent out to the browser. Is there any way to make php/apache output the html to the browser as it is generated by the script? If not can anyone suggest any other methods of getting the final result that I'm looking for?