A friend of mine told me she had Windows XP AND Windows 7 on her computer. I have not seen it.

I got a new DELL 660 last year with Windows 7 on it. I am trying to learn how to use it for everything, but I really miss my XP! And my all-in-one printer will not do everything with Windows 7.

Is it safe to install Windows XP on my new computer? How does that work? How do you know which system you are using at any given time?