Guid.TryParse()

Are you ever passed GUID’s via a query string? How can you trust that it is a real GUID? I want to be able to do this

Guid result;
if (GuidHelper.TryParse(Request["ID"], out result))
    return result;
else
    return null;

I have to parse Guids occasionally so I wrote this little helper to add to where the .Net Framework is lacking.

public static class GuidHelper
{
        private static Regex guidFormat = new Regex(
        "^[A-Fa-f0-9]{32}$|" +
        "^({|\\()?[A-Fa-f0-9]{8}-([A-Fa-f0-9]{4}-){3}[A-Fa-f0-9]{12}(}|\\))?$|" +
        "^({)?[0xA-Fa-f0-9]{3,10}(, {0,1}[0xA-Fa-f0-9]{3,6}){2}, {0,1}({)([0xA-Fa-f0-9]{3,4}, " +
        "{0,1}){7}[0xA-Fa-f0-9]{3,4}(}})$",
        RegexOptions.Compiled|RegexOptions.CultureInvariant|RegexOptions.Singleline);


    /// <summary>
    /// Converts the string representation of a Guid to its Guid 
    /// equivalent. A return value indicates whether the operation 
    /// succeeded. 
    /// </summary>
    /// <param name="value">A string containing a Guid to convert.</param>
    /// <param name="result">
    /// When this method returns, contains the Guid value equivalent to 
    /// the Guid contained in <paramref name="value"/>, if the conversion 
    /// succeeded, or <see cref="Guid.Empty"/> if the conversion failed. 
    /// The conversion fails if the <paramref name="value"/> parameter is a 
    /// <see langword="null" /> reference (<see langword="Nothing" /> in 
    /// Visual Basic), or is not of the correct format. 
    /// </param>
    /// <value>
    /// <see langword="true" /> if <paramref name="value"/> was converted 
    /// successfully; otherwise, <see langword="false" />.
    /// </value>
    /// <exception cref="ArgumentNullException">
    ///        Thrown if <pararef name="value"/> is <see langword="null"/>.
    /// </exception>
    public static bool TryParse(string value, out Guid result)
    {
        if (!string.IsNullOrEmpty(value))
        {
            Match match = guidFormat.Match(value);
            if (match.Success)
            {
                result = new Guid(value);
                return true;
            }
        }
        result = Guid.Empty;
        return false;
    }
}