Batch file to automatically detect, download and install PowerShell 2 on to an XP SP3 machine

RequiresPowerShell.bat

REM Based on http://blog.codeassassin.com/2009/12/10/no-web-browser-need-powershell/

@echo off

ver | find "XP" > nul
if %ERRORLEVEL% neq 0 goto not_xp

if not exist %SystemRoot%\system32\WindowsPowerShell\v1.0\powershell.exe goto install

%SystemRoot%\system32\WindowsPowerShell\v1.0\powershell.exe -command "exit $PSVersionTable.PSVersion.Major"
set PSVer=%errorlevel%
if %PSVer% geq 2 goto already_installed

echo PowerShell %PSVer% is currently installed (but will be upgraded)

:install
echo Downloading PowerShell 2
echo class Program { public static void Main() { >"%~dpn0.cs"
echo using (var wc = new System.Net.WebClient()) { >>"%~dpn0.cs"
echo wc.UseDefaultCredentials = true; >>"%~dpn0.cs"
echo wc.DownloadFile(@"http://download.microsoft.com/download/E/C/E/ECE99583-2003-455D-B681-68DB610B44A4/WindowsXP-KB968930-x86-ENG.exe", @"%~dpn0.installer.exe");}}} >>"%~dpn0.cs"
"%systemroot%\microsoft.net\framework\v3.5\csc.exe" /out:"%~dpn0.exe" "%~dpn0.cs"
"%~dpn0.exe"
echo Installing PowerShell 2
"%~dpn0.installer.exe"
goto exit

:not_xp
echo This script only expects to work on XP, which is not your OS.
echo Install PowerShell manually from http://microsoft.com/powershell
goto exit

:already_installed
echo PowerShell 2 or higher is already installed at %SystemRoot%\system32\WindowsPowerShell\
goto exit

:exit