WARNING : You must install Visual C++ 2010 SP1 Redistributable Package x86 or x64
VC10 SP1 vcredist_x86.exe 32 bits : http://www.microsoft.com/download/en/details.aspx?id=8328
VC10 SP1 vcredist_x64.exe 64 bits : http://www.microsoft.com/download/en/details.aspx?id=13523

WARNING : Do not try to install WampServer 2 over WAMP5.
If WAMP5 is installed on your computer, save your data, uninstall it and delete the WAMP5 directory before installing WampServer 2.

WARNING : All the components of the v2.2 WampServer stack have been compiled with VC9 version of Microsoft compiler.
Earlier versions of Wampserver have been made with VC6 version of Microsoft compiler.
So, You can't mix components of 2.2 stack with previous version of Wampserver Stack components.
If you do it you will get an instable Wampserver.