How gradually to install programs using vb script?

Hi Experts,
 my script has to verify the existence of individual programs (whether they are installed on your computer). If they are installed, so the script is skipped. If the computer programs are missing, they run sequentially unattended installation.
 The script must handle:
 1) simply check the existence of programs (installation path can sometimes be even more -see my script)
 2) easy to add a new program to the list of programs to install
 3) gradually start installing individual programs with pre-determined parameters unattended
4) List MsgBox number of programs that need to be installed - for example, the script detects that your computer is missing installed 2 programs and shows MsgBox "Number of programs for installation: 2"

Dim objFSO, oShell, APP_Gimp_PATH_1, APP_Gimp_PATH_2

APP_Gimp_PATH_1 = "C:\Program Files\GIMP 2\bin\gimp-2.8.exe"
APP_Gimp_PATH_2 = "C:\Program Files (x86)\GIMP 2\bin\gimp-2.8.exe"

Set oShell= Wscript.CreateObject("WScript.Shell")
Set objFSO = CreateObject ("Scripting.FileSystemObject")
  
  If (objFSO.FileExists (APP_Gimp_PATH_1) Or objFSO.FileExists (APP_Gimp_PATH_2)) Then 
      MsgBox "The program is installed."
  Else 
oShell.Run "RunAs /user:admin@mydomain ""\\192.168.1.5\i$\INSTALL\GIMP\gimp-2.8.2-setup-1.exe /SILENT /NOCANCEL /NORESTART"""  
End If

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Thank you very much in advance for your help and advice myself I would not make it unfortunately.
TM