Information Management Software

I am looking for a piece of software that will manage information and ideas in a treeview, similar to how windows explorer displays your files. We want to manage software ideas, notes, bugs…ect for multiple users. I have been using a program called ECCO if you are familiar with it and it worked okay, but I am getting to the point where I have too much information and it is no longer supported by the company that wrote it.

I did a quick search through tucows but didnt find anything that met my needs, any suggestions?

Thanks

Ziggy
Serpico