What do I need to open Office files .xls .ppt etc

[Mark]

I have an Application Server, that has a shared Network drive "S" Drive

We store .pdfs .xls .xlxs an office docs on the server.

We try and open Office documents from local clients on the local network.
They open S open the files, and can open .doc's but when they try and opn
..xlx, .ppt etc..it says open with.

Do I need a copy of Office on The Server? Do I need to make a registry entry?

What would I need to install?

Furthermore, I log in via remote web workplace click the file and can't open
them.. Is there a way.

I need to open all types of Pffice Docs.

Thanks

Mark