VBScript - Switching to specific IE7 tab

Dim tabnumber,Found
tabnumber = 0

set shell = CreateObject("WScript.Shell")
Set objShell = CreateObject("Shell.Application")
Set objShellWindows = objShell.Windows

If objShellWindows.Count = 0 Then
    Wscript.Echo "No browser windows are open at Yahoo"
    Wscript.Quit
End If

Found = False

For i = 0 to objShellWindows.Count - 1
    Set objIE = objShellWindows.Item(i)
    strURL = objIE.LocationURL
    If InStr(strURL, "http://www.yahoo.com") Then
        Found = True
        tabnumber = i
    End If
Next

If Found Then
    Wscript.Echo "You Already have a window open at Yahoo"
    set objIE = objshellwindows.Item(tabnumber)
    shell.AppActivate objIE.locationName
    shell.sendkeys "% x"  'Maximize window
Else
    Wscript.Echo "No browser windows are open at Yahoo"
End If