I started using Groove and I have to admit that I like it. If you need to share you have to take a look at it - there is a 30 day trial version I think.
Briefly: Groove is modular - it has a concept of tools where each tool defines functionality such as discussions, file sharing, calendar, chat, etc. You wrap selected tools into a workspace which is shared across members. There is also security management which gives different permissions to each member. Groove allows you to share a file folder easily, too.
Certainly a product worth looking at.