Yes, make it a submit button. Just out of interest, if you did want to disable the enter key, you could do this:
<input id="password" type="text" name="password" size="20" onkeypress="return handleEnter(this, event)">
function handleEnter(field, event)
if(event.keyCode == 13) // Enter has been pressed
However, I do not recommend doing this since the problem can be solved in 6 letters (submit).