I had DOT NET version 4.0 installed. Then, I've installed 2.0 especially for the program, but it still shows that version 2.0 is required.
Version 2.0 of Net Framework is required for Windows XP only. For other versions of the Windows operating system, you need Net Framework 4.0+.
However, they provide a link to the correct version of Net Framework that has to be installed on the PC where Bluestacks will be installed as well.
Download from Microsoft: http://download.microsoft.com/download/c/6/e/c6e88215-0178-4c6c-b5f3-158ff77b1f38/NetFx20SP2_x86.exe