This is what I'm using.  I borrowed it from somewhere, but not sure where:
using System.Collections.Specialized;
using System.Text.RegularExpressions;
/// <summary>
/// Parses the command line arguments into a name/value collection
/// </summary>
public class CommandLineArgumentParser
{
    #region Fields
    private StringDictionary parameters;
    #endregion
    #region Constructors
    /// <summary>
    ///     Initializes a new instance of the <see cref="CommandLineArgumentParser"/> class.
    /// </summary>
    /// <param name="args">command-line arguments
    /// </param>
    public CommandLineArgumentParser(string[] args)
    {
        this.parameters = new StringDictionary();
        Regex spliter = new Regex(@"^-{1,2}|^/|=|:", RegexOptions.IgnoreCase | RegexOptions.Compiled);
        Regex remover = new Regex(@"^['""]?(.*?)['""]?$", RegexOptions.IgnoreCase | RegexOptions.Compiled);
        string parameter = null;
        string[] parts;
        // Valid parameters forms:
        // {-,/,--}param{ ,=,:}((",')value(",'))
        // Examples: 
        // -param1 value1 --param2 /param3:"Test-:-work" 
        //   /param4=happy -param5 '--=nice=--'
        foreach (string txt in args)
        {
            // Look for new parameters (-,/ or --) and a
            // possible enclosed value (=,:)
            parts = spliter.Split(txt, 3);
            switch (parts.Length)
            {
                // Found a value (for the last parameter 
                // found (space separator))
                case 1:
                    if (parameter != null)
                    {
                        if (!this.parameters.ContainsKey(parameter))
                        {
                            parts[0] = remover.Replace(parts[0], "$1");
                            this.parameters.Add(parameter, parts[0]);
                        }
                        parameter = null;
                    }
                    // else Error: no parameter waiting for a value (skipped)
                    break;
                // Found just a parameter
                case 2:
                    // The last parameter is still waiting. 
                    // With no value, set it to true.
                    if (parameter != null)
                    {
                        if (!this.parameters.ContainsKey(parameter))
                        {
                            this.parameters.Add(parameter, "true");
                        }
                    }
                    parameter = parts[1];
                    break;
                // Parameter with enclosed value
                case 3:
                    // The last parameter is still waiting. 
                    // With no value, set it to true.
                    if (parameter != null)
                    {
                        if (!this.parameters.ContainsKey(parameter))
                        {
                            this.parameters.Add(parameter, "true");
                        }
                    }
                    parameter = parts[1];
                    // Remove possible enclosing characters (",')
                    if (!this.parameters.ContainsKey(parameter))
                    {
                        parts[2] = remover.Replace(parts[2], "$1");
                        this.parameters.Add(parameter, parts[2]);
                    }
                    parameter = null;
                    break;
            }
        }
        // In case a parameter is still waiting
        if (parameter != null)
        {
            if (!this.parameters.ContainsKey(parameter))
            {
                this.parameters.Add(parameter, "true");
            }
        }
    }
    #endregion
    #region Properties
    /// <summary>
    /// Gets a count of command line arguments
    /// </summary>
    public int Count
    {
        get
        {
            return this.parameters.Count;
        }
    }
    /// <summary>
    /// Gets the value with the given parameter name
    /// </summary>
    /// <param name="param">name of the parameter</param>
    /// <returns>the value of the parameter</returns>
    public string this[string param]
    {
        get
        {
            return this.parameters[param];
        }
    }
    #endregion
}