Popup vs blank Form in a Forms App

Question

I have a Forms (VS2008, C#,  Access DB) application which I am nearing the end of development on and 1 of the tasks left is to open some sort of PopUp type window to display some data DB in.  The window will have data displayed in it depending on what item in a ListBox the user hovers the mouse over.
I was considering a Form with no caption or controls on it to make it look like a Popup window.  Then I read about the Popup window control.
Has anyone done anything like this?  Which is best (easist) to use the PopUp control or a Form?
Thanks