That is what we tried first . . . it didn't work. We had to create new files for each of the '07, '08 and '09 releases. No idea why, but poining to the old files did not work correctly.
Wow. We've used basically the same ones since 2004 with no issues, except one...
Our Canon large-format printer had issues printing with the 2006 release of software. We had to set it up in some funky manner, such as select portrait instead of landscape in the PC3 file, and then it worked the way we wanted. This problem did not exist in the 2007 software, so we had to change that printer's PC3 file when we installed 2007, and set it up the way it should've been in the first place, except for the weird behavior in 2006.
The really funny part was that as soon as we installed 2007 on a computer, it fixed the printing issue in 2006, too. I'm guessing Autodesk updated something in the Autodesk Sabotage (aka Autodesk Shared) directory between the 2006 and 2007 releases, and in this case, it actually fixed a problem in 2006, instead of creating one.
Other than that, I'm pretty sure all our page setups, PC3s, and PMPs have been basically the same since 2004...