Let me clear up some confusion that people are taking away from the ReadMe's regarding Uninstalling 2.8 prior to installing 3.0..........  

Here are the “instructions”  (step 1 is clarified):

1. Before installing Media Composer 3.0, you need to uninstall your old verison of Media Composer and any version of FilmScribe, EDL Manager, MediaLog, and Avid Log Exchange.

2. Remove the following Registry keys on your system if they still exist after the uninstallation process.

HKLM/Software/Avid Technology/<productname>

HKLM/Software/Avid Technology/AVX Plug-ins

3. From the following folders, remove any folders that do not have custom data in themthat you want to keep. If you do have custom data, copy the data to the new locations after step 4.

C:/Documents and Settings/AllUsers/ApplicationData/Avid/<productname>

C:/Program Files/Avid/<ProductName>

(Vista) C:/ProgramData/Avid/<Productname>

4. Install the new Avid editing application.

HTH

Marianna