If the wamp server installation popup "MSVCR100.dll' is missing"error, You can solve this by the following methods.
The MSVCR100.dll file is part of the Microsoft Visual C++ 2010 redistributables. Download and install the appropriate version to solve the issue.
For Windows 32 : Be sure that you have installed the Visual C++ 2010 SP1 Redistributable Package x86 : VC10 SP1 vcredist_x86.exe
For Windows 64 : Be sure that you have installed the Visual C++ 2010 SP1 Redistributable Package x64 : VC10 SP1 vcredist_x64.exe