2 accounts on same computer???

hi,

My wife got a new ipod for christmas, ive set up an account for her but i also have an account as i already had an ipod.

When i log out of my account my playlist is still there, if i sign my wife in my playlist is still there again.

If i plug her ipod in will that delete my tunes??

Can we have 2 accounts on the same computer??

Thanks and have a happy new year

Chris