Howtoforge posted a tutorial about setting up Ubuntu 11.10 (Oneiric Ocelot) desktop as a full-fledged replacement for a Windows desktop

This tutorial shows how you can set up an Ubuntu 11.10 (Oneiric Ocelot) desktop that is a full-fledged replacement for a Windows desktop, i.e. that has all the software that people need to do the things they do on their Windows desktops. The advantages are clear: you get a secure system without DRM restrictions that works even on old hardware, and the best thing is: all software comes free of charge.

Ubuntu 11.10 will by default start the new Unity desktop which requires that your hardware supports 3D acceleration, however you can also switch to Unity 2D mode in the log on screen. If your hardware does not support 3D acceleration or you don't like Unity, you can still download the Ubuntu Classic GNOME desktop, what I will do later in this tutorial.

I want to say first that this is not the only way of setting

  The Perfect Desktop - Ubuntu 11.10 (Oneiric Ocelot)