My application uses both versions 3.5.0.0 and 3.5.1.0 of System.Data.SqlServerCe.dll so I have to install sql server compact 3.5 sp1. In vs2008, only sql server compact 3.5 can be selected as prerequisite if "from the the application location" is chosen. The workaround would be replacing the sql server compact edition 3.5 with 3.5.1. It's important that the two versions must be of the same file name as they can be downloaded from Microsoft website with different names. Otherwise the installer will complain that the file is not found. This operation can be set in PostBuildEvent. I think there might be an easier way. Can you please comment?

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Sql server compact 3.5 sp2 is also packed in a similar way, one for x86 and the other for x64. I think renaming the file is not a big deal. The installer may also need to detect whether the target OS is 64 bit and install the right SSCE runtime.