Hi Pat, welcome to the forums.
Adobe can be a real pain with this as you can only run older versions of ACR in older versions of PS (meaning that if you buy a new camera you, theoretically,
have to buy new softwarwe!).
However, I
think that ACR4.6 will work in PSE5. The official Adobe download page and instructions are
here. Follow the instructions for Elements 6.0 and (apparently) it will work for Elements 5.
I got this info from the Elements Village forums
(link). They might be worth checking out!