public static ProcessStartInfo ParseCommandLine(string command)
{
    string[] segments = command.Split(new[] { '"' }, StringSplitOptions.RemoveEmptyEntries);
    string filename = "";
    string args = "";
    if (segments.Length == 1)
    {
        filename = segments[0];
    }
    else if (segments.Length == 2)
    {
        filename = segments[0];
        args = segments[1];
    }
    return new ProcessStartInfo(filename.Trim(), args.Trim());
}

var test = ParseCommandLine("C:/my/long/path/executable.exe \"omg\"");
//test.fileName == "C:/my/long/path/executable.exe"
//test.Arguments == "omg"