Internal opensource web-based office solution [closed]

I am looking for an open source equivalent to Google Docs that can be locally hosted. Does anyone have any experience in using any open source web office solutions?

The key features I am looking for are

• Runs on Linux
• Supports importing .xls spreadsheets
• Easy to setup
• Intuitive interface

www.opengoo.org is a project striving to recreate much of the Google Docs experience (including mail integration).

I'm not sure about the importing of XLS documents. I haven't quite made it that deep into the demo.