Elements 2.0 upgrade

What is your operating system?

As hatstead suggests, you should be eligible for an "upgrade" discount from Adobe even with version 2 of the program.  (On the Adobe purchase dialog you will be asked whether you own a previous version of Photoshop Elements, and I can find nothing on the webpage that suggests this eligibility is limited in any way.)

If you are using the Elements 2 Organizer - I don't recall whether it was still called Photoshop Album back then - there will be some extra steps you need to take to convert it to the latest database format.  See this article for more information.

Added: And just to avoid some confusion created by the marketing department, the latest version of Elements is Elements 2022.  It is in fact version 20. 

You can "upgrade" by purchasing the current version  -  PSE 22. If your old version is installed on your computer, it will not be over-written, as each version of the software in independent.