I wonder if anyone has done this before.
I have recently built a new computer it is an upgrade from an older home server that died, the plan is that it is going to consolidate a few computers into one, and be multipurpose.

The setup is as following:
Ubuntu 12.04

Asus Motherboard P8H77-I
CPU: Intel Core i7 3770 3,4GHz
Ram: 16GB DDR3 1600MHz
GFX: Integrated Ivy Bridge Graphics Controller

Main purpose is a home server, this is already done, with a 5 disk ZFS RaidZ and a SSD system disk.

Second purpose is a desktop PC for my daughter, probably Edubuntu or similar, this is partially done, I have installed Ubuntu Desktop, but have not added the Edu suite yet.
It has an LCD connected to the VGA port, a wireless USB keyboard/mouse and speakers connected to the audio port on the back.

Third purpose is an HTPC, this is the one i'm wondering how to do.
Currently the TV is connected via an HDMI cable, and it is mirroring or extending the Ubuntu Desktop to the TV depending on the setting in System settings but only in the LCD screens resolution, I can also switch the audio to the HDMI to the TV from the Sound Settings.
The plan is to use XBMC for this, probably with a Remote, or small keyboard to control it.
But I still also want a separate desktop on the TV.

But how do I create a separate environment for the TV and the Desktop.
So that the TV has it's own Screen/Audio/Keyboard/Mouse?