Automating the Title Column in SharePoint 2007

I am working on editing a list on SharePoint 2007. I want to make the title column automatically generate a new sequential number each time a new task is to be performed. How do I automate the title column or any column to give an incremental number whenever a new task is to be filled in or performed?

for example: First task: Title= 1909

Second task: Title= 1910 Third task: Title= 1911