Bought the retail version today, after much thought. Had the EXACT same problem as everyone on here. I had the typo with the CD Key and after trying every way possible I found this worked. By the way, I only installed this once, I did not delete it and re install:
CD KEY was 6-5-5-5-4
I shifted all the characters along as described by previous posters
Example: CD KEY on back of book : AAAAAB - BBBBC - CCCCD - DDDDE - EEEE
I Changed it to : AAAAA - BBBBB - CCCCC - DDDDD - EEEEE
BUT, The most important part of this, and the main reason it was not accepting the code is because you cannot distinguish between the LETTER O and the NUMBER 0
I found after trying every combination of O and 0 that eventually it worked.
After looking a lot closer at this, the LETTER O is "thinner" than the NUMBER 0, and as mentioned before, the letter O has straighter sides.
This is only a very slight difference and you do need to look closely. Failing that, just keep trying the password with every combination of 0 and O possible.
Hope this helps someone