How to Verify you have .NET 3.5 SP1

Today I was asked how I could verify .NET 3.5 SP1 installed successfully on several PCs running Windows XP Professional.  I searched the Internet and found several answers:

• Check Add Remove Programs under Control Panel
• Open Internet Explorer and enter this Javacript in the url bar:       javascript:alert(navigator.userAgent)
• Open the registry and look for this key  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform\.NET CLR 3.5.30729
• Finally click on Start => Run and enter C:\Windows\Microsoft.Net\Framework\v3.5.  You should see a folder called Microsoft Framework 3.5 SP1

Thanks to Walker News for the information.