Install PowerShell 4.0

<#
This script checks for the PowerShell version, and if it's not 4, downloads and installs PS 4.0. Uses the PS 2 download function instead of the usual one.

You need both the x64 and x86 versions of Windows Management Framework 4.0, and the .Net Framework 4.5.1 from the URLs you specify below.
I have a private URL where I put downloads for my scripts, so I download them from MS and upload them to my FTP server. You may be able to download directly from MS in the scripts.

You can download them from here:
Windows Management Framework 4.0: http://www.microsoft.com/en-us/download/details.aspx?id=40855
.Net Framework 4.5.1: http://www.microsoft.com/en-us/download/details.aspx?id=40779
#>

#Set these variables to the URL to download .Net 4.5 and MS Management. Don't fill in the filenames and don't put a trailing slash.
$DotNetUrl = "http://yoururl.com"
$WMFUrl = "http://yoururl.com"

#Functions start here
#**********************************************************************************************************************************************

#PS 2.0 download function
Function get-FileFromUri {
# This function downloads a file in PowerShell 2.0.
# Example: get-FileFromUri http://example.com/url/of/example/file C:\example-folder
param(
[parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]
[string]
[Alias('Uri')]
$Url,
[parameter(Mandatory=$false, Position=1)]
[string]
[Alias('Folder')]
$FolderPath
)
process {
try {
# resolve short URLs
$req = [System.Net.HttpWebRequest]::Create($Url)
$req.Method = "HEAD"
$response = $req.GetResponse()
$fUri = $response.ResponseUri
$filename = [System.IO.Path]::GetFileName($fUri.LocalPath);
$response.Close()
# download file
$destination = (Get-Item -Path ".\" -Verbose).FullName
if($FolderPath) { $destination = $FolderPath }
if ($destination.EndsWith('\')) {
$destination += $filename
} else {
$destination += '\' + $filename
}
$webclient = New-Object System.Net.webclient
$webclient.downloadfile($fUri.AbsoluteUri, $destination)
write-host -ForegroundColor DarkGreen "downloaded '$($fUri.AbsoluteUri)' to '$($destination)'"
} catch {
write-host -ForegroundColor DarkRed $_.Exception.Message
}
}
}
#*****************************************************************************************************************************************************
#End of functions

#Script Start

#Determines Powershell version. Exits the script if it's 4.0
if ($PSVersionTable.PSVersion.Major -ge 4) {
$Date = Get-Date
Write-Host "$Date - Powershell upgrade not needed. Exiting script."
Exit
}

#Determines if DotNet 4.5 is installed, downloads and installs if it is not.
$DotNetVer = (Get-ItemProperty -Path  "HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Client").Version
If ($DotNetVer -lt 4.5){
    $FileUrl = "$DotNetUrl/NDP451-KB2858728-x86-x64-AllOS-ENU.exe"
    $FileDest = "$env:Temp"
    $Date = Get-Date
    Write-Host "$Date - Downloading the .Net Framework 4.5 installer"
    Get-FileFromUri $FileUrl $FileDest
    Set-Location "$env:Temp"
    $Date = Get-Date
    Write-Host "$Date - Installing .Net Framework 4.5. This can take some time. The script will continue when it's finished."
    .\NDP451-KB2858728-x86-x64-AllOS-ENU.exe /q /norestart | Out-Null
    #Checks to make sure it installed, exits with an error if not
    $DotNetVer = (Get-ItemProperty -Path  "HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Client").Version
    If ($DotNetVer -lt 4.5){
        $Date = Get-Date
        Write-Host "$Date - Install of Dotnet Framework 4.5 failed with error code: $LastExitCode - Exiting the script."
        Exit 1000
        }
    Else {
    $Date = Get-Date
    Write-Host "$Date - Install of Dotnet Framework 4.5 succeeded"
    }
}

#Determines the architecture of the machine
$Arch = (Get-WmiObject Win32_OperatingSystem).OSArchitecture
#Sets the name of the Windows Management Framework installed based on architecture
If($Arch -eq "64-Bit") {$WMF = "Windows6.1-KB2819745-x64-MultiPkg.msu"}
    Else {$WMF = "Windows6.1-KB2819745-x86-MultiPkg.msu"}

#Downloads and silently installs Windows Management Package
$FileUrl = "$WMFUrl/$WMF"
$FileDest = "$env:Temp"
$Date = Get-Date
Write-Host "$Date - Downloading the Windows Management Package installer."
Get-FileFromUri $FileUrl $FileDest
Set-Location "$env:Temp"
$Date = Get-Date
Write-Host "$Date - Installing the Windows Management Package."
wusa.exe "$WMF" /quiet /norestart | Out-Null

#Checks to see if the installed succeeded. When it succeeds, it returns error 3010, which means the computer needs to be rebooted.
If($LastExitCode -eq 3010) {
$Date = Get-Date
Write-Host "$Date - The install of Powershell 4.0 finished. The workstation will need to be rebooted before the changes apply."
}
    Else {
    $Date = Get-Date
    Write-Host "$Date - The install of Powershell 4.0 failed with error code: $LastExitCode - You may need to manually install."
    Exit 1000
    }