I noticed you changed the port that the Arduino server is listening on. If you would rather have it listen on port 23 instead of 80, you will need to make a change to the PHP code so it looks for the arduino on the correct port. Hopefully that helps!

Dan

However I folowed another example and worked fine.

Is there any kind of test that could I do?

Here is the code that worked:
Upload to arduino and browse the indicated IP (you can change to fit better your network)

// you can change this line if you want to serve, for example, XML or some other content type
#define HTTP_HEADER “HTTP/1.0 200 OK\r\nServer: arduino\r\nContent-Type: text/html\r\n\r\n”

void setup(){
setupEthernet(”010.000.000.011″, 80); // Arduino IP 10.0.0.11
}

void loop(){

//put your code here

// then check for requests, and if so, serve the webpage
if (ethernetRequest()){
writeHeader();
writePage(”Seja bem vindo ao Arduino!”);
writePage(”Valores analogicos que estou lendo:”);
for (int i = 0; i < 6; i++)
{
writePage("”);
writePage(analogRead(i));
}
servePage();
}
}

Here is your example. See if do I have to make some change, please. The IP I need to use is 10.0.0.11 (255.0.0.0):

// Arduino_live_gauge
// =======================================================================================
// This sketch takes puts the information on A5 out through the ethernet connection when
// there is a connection on port 23. There is a corresponding script that connects, then
// displays the information in a gauge via PHP and Open Flash Gauges
// (http://www.digitaldarknet.net/flash/).
//
// Written By: Dan Wagoner – http://www.nerdybynature.com
// Date: 07/26/2009

#include
#include
#include

//LED de teste
int LED = 7;

// define ethernet properties

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
//byte ip[] = { 192, 168, 1, 10 };
byte ip[] = { 10, 0, 0, 11 }; //ip que eu escolhi
byte gateway[] = { 10, 0, 0, 138}; //gateway
//byte subnet[] = { 255, 255, 255, 0};
byte subnet[] = { 255, 0, 0, 0}; //mascara da minha rede
Server server = Server(23); // listen on port 23
//Server server = Server(80); // listen on port 80

void setup()
{
pinMode( 5, INPUT );
pinMode( LED, OUTPUT); //pino do LED
Serial.begin(9600);
Ethernet.begin(mac, ip, gateway, subnet);
server.begin();
delay(1000);
}

void loop(){

//pisca o led pra testar se o código está ok
digitalWrite (LED, HIGH);
delay(1000);
digitalWrite (LED, LOW);
delay(1000);

Client client = server.available();
if (client){
client.print(analogRead(5));
Serial.println(analogRead(5));
delay(200);
client.stop();
Ethernet.begin(mac, ip, gateway, subnet);
}
}

I am so glad I came across your site. I found you by doing a search on you-tube. Well I am starting a project that consists of two temperature sensors a PH probe and a couple digital outs for a aquarium controller. I just began the start up of a server to host the guages. I think I have followed your directions, but all I get is a blank black page. I have Ubuntu running with apache2, PHP5, and java6.

Thanks Again,
Scott