To get the system drive in C# you can use:
var p = System.IO.Path.GetPathRoot(Environment.GetFolderPath(Environment.SpecialFolder.System));
In Vb.NET:
Dim p = System.IO.Path.GetPathRoot(Environment.GetFolderPath(Environment.SpecialFolder.System))
To get the path where the exe is:
Dim strPath As String = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().CodeBase)
Your will have to remove the begin of the string "file:\\" though.