Glossary
Distro - Because Linux is free many people distribute it, and all these variants are slightly different, they may be aimed at different people, or just have a slightly different philosophy. Try as many as you want, and use the one you feel most comfortable with, there is no one best distro, just the one that is best for you. A Distro includes not just the basic system software, but almost all of the software most users will be needing initially, including MS Office compatible office applications
Emulation - a bit of software enables software for another OS to run on your computer by pretending to be that OS as far as the software is concerned, allows you to run, ie a windows game on Linux, or a Spectrum game on Windows.
Dual-booting - The given to the way of installing Linux on a computer, so that you can start up the computer and load either Linux or Windows, depending on what you want to use at the time. A very common configuration that is more than adequately handled by most Linux Distros on installation.