Optimization

If you want to use encryption with Ubuntu you have to consider 2 things:

The migration from Windows to Ubuntu is not very difficult, but also not very easy. It's like moving house, everything feels a little out of place for a while. For a smooth migration I suggest the following: 1. Install Ubuntu first as dual boot beside your Windows installation or 2. Start with Ubuntu 12.04 LTS.

If you have an old computer with limited resources you might have problems to run the recent Ubuntu releases 12.04 LTS or 13.04 smoothly. If so, I recommend you to use the derivatives Xubuntu or Lubuntu that use much less resources. While Ubuntu 13.04 is said to use around 320 MB RAM, XUbuntu 13.04 and LUbuntu 13.04 are said to use around 160 MB and 103 MB respectively.