Nullsoft SuperPiMP Install System (NSIS)
Applications packaged with NSIS supports the /S switch for a silent installation (the 'S' is case-sensitive)
You can also use the /D switch to specify a destination drive/directory to install the files into:
Setup.exe /S /D=E:\Software\CDex
Software such as Winamp and CDex show a confirmation that install was successful at the end (CDex), or an "end-of-install" screen where you set file associations and settings (Winamp). I haven't found a way to bypass this yet, but it shouldn't affect the rest of the batch commands in any way.
» How do I find out if a setup package is made by NSIS?
Many NSIS packaged installers show the familiar small window at the center of your screen, such as Winamp and CDex: