I did a default upgrade of Snow Leopard on my Mac which had Parallels 3.0 installed. I have a full retail version of Parallels 4.0 on a CD and can upgrade/install, but want to be sure I can do so without losing my XP Pro install, or any of the installed applications. I have not yet done anything to upgrade to 4.0... I want to make sure I don't foul things up is it can be avoided. -Can I now upgrade 3.0 to 4.0? -Is there a procedure? -Should I download a newer version and install it, using the key code on the box?