30 minutes of my life I'm never getting back.
Installed ADE 2.0 on my WinXP/SP2 box with ADE 1.72 already on it and running happily for months. (Note that Adobe says SP3 is a minimum requirement for an XP install but the install process did not balk, so I went ahead.)
Things seemed to go smoothly. I was asked if I wanted to transfer existing 1.72 books (I did not), and my security program alerted me that a program called "migrate" wanted to run. I allowed it, and post-install, ADE 2.0 informed me that it was successfully authorized with my existing Adobe ID.
However, every graphic (book covers, interface buttons, etc.) was scrambled. Tried to open a newly downloaded library book, and the contents were also scrambled. Life, being as short as it is, lead me to just uninstall ADE 2.0. It went smoothly and I did not have to reauthorize 1.72. I re-downloaded the same library book and 1.72 performed as usual.
I see from some postings that people deauthorized 1.72 first, then authorized 2.0 by hand, but as far as I'm concerned, Adobe should tell one that. And if 2.0 won't work on a particular SP of an OS, Adobe should flag that during install, also. That ain't rocket science. (FWIW, my interface graphics (buttons, menus) were distorted before I downloaded any content. The "migrate" program was already complete.)
Adobe products have been a PITA for years and years. The tradition continues.