Calling a .vbs script from Excel VBA
I only want to add to Alex' answer, that in some environments the object must be created in the following way:
set scr = CreateObject("MSScriptControl.ScriptControl")
If Alex adds this to his answer, I will delete this one.
To run a file:
Shell "wscript c:\null\a.vbs", vbNormalFocus
replacing wscript
with cscript
if the VBS wants to use the console.
Or you can add a reference to the Microsoft Script Control and interact with the VBScript runtime directly to execute VBS code, procedures etc;
Dim scr As ScriptControl: Set scr = New ScriptControl
scr.Language = "VBScript"
scr.AddCode "sub T: msgbox ""All Hail Cthulhu"": end sub"
scr.Run "T"