Refresh a Powerpoint Presentation when a new version appears.

The purpose of this code is to run a powerpoint presentation in a kiosk, but check every half hour to see if there are updates. If there are, the script kills the current presentation, backs up the current presentation, then copies the new presentation over the current one and re-starts the viewer. My apologies if the format makes people twitch; I came from a C-based programming environment before someone asked me to write my very first VBScript.
 
Your comments and feedback to streamline the code and make me a better scripter would be greatly appreciated.
 
EDIT: Wow, the code viewer really doesn't like my formatting. If it's unreadable, I'll just delete it.
 



 ' ------------------------------ Launch_PPT_ThinClient.cmd --------------------------- 
' 
'  
' Batch Command to launch a powerpoint presentation, then sleep and restart the 
' presentation periodically. 
' 
' Original Author: Bryan X 
' Rewritten by:  Michael X 
' 
' Originally Created: 5/23/2011 
' Rewritten on:  9/21/2011 
' 
' Usage: This batch command is started by including a shortcut in the user 
' profile's startup folder 
' 
' History: 
'   Version 1.0 - Original Release 
'  Version 2.0 - Test Release 
'  Version 2.1 - Production Release 
' 
' Notes: The powerpoint file must reside in a specific location that the service 
' account has read access to. In order for the viewer to loop the presentation, 
' the Slide Show settings must conform to Show type: Presented by a speaker and 
' Show options Loop continuously until 'Esc'. No other settings appear to work 
' in test. 
'   
' ----------------------------- Launch_PPT_ThinClient.cmd ------------------------------ Option Explicit 'Enforce strict coding Dim CFO, LFO, NFO 
Dim CF, LF, NF 
Dim NewPresentation 
Dim currentfile, logfile, oldfile, newfile, PPT 
Dim WhoAmI     Function Launch_Presentation() 
 Dim WshShell : Set WshShell = WScript.CreateObject("WScript.Shell")     NewPresentation = Null 
 WhoAmI = WshShell.ExpandEnvironmentStrings("%USERNAME%") 
 currentfile = "C:\Documents and Settings\" & WhoAmI & _ 
"\Desktop\SITECOMMUNICATION.PPT" 
 oldfile = "C:\Documents and Settings\" & WhoAmI & _ 
"\Desktop\SITECOMMUNICATION_OLD.PPT" 
 logfile = "C:\Documents and Settings\" & WhoAmI & _ 
"\Desktop\Update_Log.txt" 
 newfile = "G:\communication\Newtvupdate\Newplasma.ppt" 
 PPT= """C:\Program Files\Microsoft Office\Office14\PPTVIEW.EXE""" Check_Presentation   Run_Presentation 
End Function     Sub Replace_Presentation() 
 Set CFO = CreateObject("Scripting.FileSystemObject") 
 Set LFO = CreateObject("Scripting.FileSystemObject") 
 Set NFO = CreateObject("Scripting.FileSystemObject") 
 Set LF = LFO.OpenTextFile(logfile, 8, True) 'Keep a log of when updates occur. 
 Set NF = NFO.GetFile(newfile) 
 NewPresentation = "Replaced"     Kill_Presentation 'Turn off the PPTVIEWer so we can relaunch with the new file.      If CFO.FileExists(currentfile) Then 
    Set CF = CFO.GetFile(currentfile) 
    CF.Copy oldfile, True 'Back up presentation 
   End If 
 NF.Copy currentfile, True 'Replace presentation 
 LF.WriteLine("Presentation file updated: " & Now())     Set CF = Nothing : Set CFO = Nothing : Set LF = Nothing : Set LFO = Nothing 
 Set NF = Nothing : Set NFO = Nothing 
End Sub     Sub Kill_Presentation() 'Find the Powerpoint Viewer under local username and kill it. 
 Dim objProcess 
 With GetObject("winmgmts:root\cimv2") 
  For Each objProcess in .ExecQuery ("SELECT commandline FROM Win32_Process" _ 
   & " Where Name = 'PPTVIEW.EXE'",,48) 
   With .ExecMethod ("Win32_Process.Handle=" & objProcess.Handle & "", "GetOwner") 
    If Lcase(.User) = WhoAmI Then 
     objProcess.Terminate() 
    End If 
   End With 
  Next 
 End With 
 Set objProcess = Nothing 
End Sub     Sub Script_Sleep() 
 WScript.Sleep 1800000 'Sleep for 30 minutes. 
 Check_Presentation 
 If IsNull(NewPresentation) = True Then 
  Kill_Presentation 
  WScript.Sleep 500 
  Run_Presentation 
 Else 
  Script_Sleep 
 End If 
End Sub     Sub Run_Presentation() 
 Dim WshShell : Set WshShell = WScript.CreateObject("WScript.Shell") 
 WshShell.Run PPT & " """ & currentfile & """" 
 WScript.Sleep 50 
 WshShell.AppActivate "SITECOMMUNICATION.PPT - Microsoft PowerPoint Viewer" 
 WScript.Sleep 100 
 WshShell.SendKeys "{F5}" 'We have to send this key command in order to enable looping. 
 NewPresentation = Null 
 Set WshShell = Nothing 
 Script_Sleep 
End Sub     Sub Check_Presentation() 
 Set NFO = CreateObject("Scripting.FileSystemObject") 
 Set CFO = CreateObject("Scripting.FileSystemObject")    If Not NFO.FileExists(newfile) Then 
  WScript.echo "Create a new presentation named " & newfile & "." 
  WScript.quit 
 End If  If Not CFO.FileExists(currentfile) Then 
  Replace_Presentation 
 End If  Set NF = NFO.GetFile(newfile) 
 Set CF = CFO.GetFile(currentfile)     If NF.DateLastModified > CF.DateLastModified Then 
   Replace_Presentation 
  End If 
 Set CF = Nothing : Set CFO = Nothing : Set NF = Nothing : Set NFO = Nothing 
End Sub     Launch_Presentation