When we installed Project 2007 on a machine with Office 2003 already installed, the Datasheet view didn't work anymore: "The list cannot be displayed in Datasheet view for one or more of the following reasons: A datasheet component compatible with Windows SharePoint Services is not installed, your browser does not support ActiveX controls, or support for ActiveX controls is disabled".
Apparently, the Datasheet view component does not work when Office 2003 and Office 2007 components both are installed on the client machine.
This is the solution:
1. Install Office 2003, include the Windows SharePoint Services Support
2. Install the Office 2007 component(s) (in my case, this was Project 2007), without Windows SharePoint Services Support!
3. Now re-run the Office 2003 installation. Choose Repair and then select the Reinstall option.
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