I got introduced to trello today and like it, look at this also, I think I'll be rolling it out across the board and it's free

Assembla.org has a complete assortment of integrated tools namely free SVN repositories, tickets, etc.

Otherwise, Trello is good for keeping track of tasks, but not files.

Basecamp might also work, assuming you have the necessary space to attach the files to the threads and todos directly.