Question about un-installing Parallels 4

I currently have Parallels 4 installed on my MacBook Pro. I just purchased a new copy of Parallels 5. Since I now own two copies of Parallels, I would like to use Parallels 4 on another computer and install Parallels 5 on my MacBook Pro.

In order to do this, do I need to un-install Parallels 4 from my MacBook Pro first, or can I install the new Parallels 5 over the old version?

I'm looking for guidance on how to do this correctly so that I can use the old and new version of Parallels properly.

Thanks.