Something worth noting when installing Crystal Reports for Visual Studio 2010 which might not be readily apparent (at least it wasn't for me). I kept installing & reinstalling Crystal Reports, but each time I tried to add a report inside Visual Studio, I got the .mht file that told me to download it. This happened for both the 32- & 64-bit installations.
It occurred to me much later that I've been installing the Redistributable packages (which is meant for deployments to servers & the like) the whole time and not the .exe that supplies the developer tools needed to create reports in Visual Studio.
Make sure to install the right package on the right machines. This link supplies a table with all the available downloads. If you want to design reports inside Visual Studio, click the link in the first column (Install Executable) to download the correct installer.