No it does not remove your version of Movie Maker, all you are doing is renaming the Movie Maker folder so that you can install version 2.0 in the same place (You cannot have two folders with the same name in the same place)
If you should wish to return to YOUR version, simply rename or delete the new Movie Maker folder then change the name of the FIRST folder you renamed back to its original name (Movie Maker)
By the way, if in your original project you had any images or sound files, you would need to find and insert them in the project.
Each of your project files I managed to open contained a single frame with a transition only and no sound...
Hope that helps..
Of course, even after doing all that, you may still not be able to open them on your computer depending on other factors like which version of XP you have, which Service Pack etc.
Sometimes it is wiser to start your projects over using the program and system you have rather than changing things around. This must be your decision of course....
Below is a screenshot of your open project showing that the audio files are missing....
