When you first installed Ubuntu you were offered the chance to set the Ubuntu hostname, which is what appears at the command-prompt and is also how your computer is identified should you activate services such as file sharing.
When a Linux users wants to get rid of a crashed program, he kills it - literally. The kill command is used for this purpose, but it needs the program ID (PID) number to work. This can be discovered using the pgrep.
Ubuntu has a powerful raft of power management features, accessible through System > Preferences > Power Management, but you might notice one missing if you're used to Windows or OS X: hard disk spin down time.
The standard method of distributing Ubuntu as a full operating system is as an ISO image, which you can burn to disc and boot from. If you need to look into what's in an ISO image you have a number of choices.
Start taking your destiny into your own hands by changing the wallpaper (er, the desktop background). If you bought a new computer with Windows 7 installed, your background text probably says Dell or Vaio or Billy Joe Bob's Computer Emporium / Dial 555-3765 for a good time.