ok i dont have maya 4.5 yet, but im pretty sure they wont take something like this away, so if it doesnt work, sorry

the property editor ur referring to is called the attribute editor, and when you hit ctrl A on an object it opens that up as well, mine doesnt open at the side it opens in a new window, i assume thats what you want to do

go to:
window>settings/preferences>preferences
and in the window near the bottom theres a bit called "Open attribute editor" then you have 2 options, 1) to open in main maya window (default, what ur ones like atm) or 2) open in seperate window (which is the one you want)