I tried to follow the tutorial on how to access to the internet from Ubuntu but couldn't do it.
I think I have an ADSL modem, but I'm not sure. How can I check that?
I tried several commands and took screenshots while in Ubuntu. For example I openened a Terminal and typed " sudo lshw -C Network"
I got "description: Ethernet interface
product: 82566DC Gigabit Network Connection
etc..." Does this help?
I've also entered to Network settings, but don't know what to change and/or type.
Please help me to go on internet via Ubuntu. If you need more information, just tell me what to type.
P.S.: I run my cpu under Windows XP.

Which tutorial? There are thousands.
Read the documentation which came with it. Read the small print on the case. Read the large print on the case. Google the product brand-name. Do you use a broadband connection?

How do you connect to the "modem"? Ethernet? Does the modem have more than one place to connect an ethernet cable to?

You need to know about your connection type - if you do not odminister the network (you didn't set it up, you don't run it, you don't own it) then you need to talk to the person who does.

I tried to follow this tutorial " https://help.ubuntu.com/7.10/internet/C/index.html" which also is on the Ubuntu live cd.
I installed myself the modem. It says it's a broadband connection, ADSL Dual modem.
I plugged the modem with a cable (look like an ethernet one, but on the "ADSL" place of my modem) into the wall joined with my phone. And the cable that is between my modem and my cpu is a USB one.
My modem has still one free place to be connected with an ethernet cable.
My connection is said to be about 1Mbits, but I guess it a bit slower than that. Hope this helps.

There you go then. Vendors like to stamp their name and a brand-name someplace too.

Use the ethernet one. The USB connection is supposed to be more reliable these days, I just have more luck with ethernet.

Plug it in - count to 20. Then enter in a terminal:

ifconfig

show us the output. If all went well it will show an IP assigned to eth0.

To configure the modem, you usually use a browser. The disk that came with the modem will have instructions for windows, read them: you'll have to translate the instructions to cross-platform language. Mostly, you need the IP of the configuration interface and the login details.

I changed the USB cable for the ethernet's one. I could access to Ubuntu, but nor my mouse nor my keyboard could then respond so I shutdown the system. It reminds me when I bought my cpu last year, I had internet via an ethernet cable and it caused me the "Blue Screen of Death". I sent my cpu to a technical and couldn't solve the problem. He told me maybe it was because of the ethernet cable, so I changed it for a USB one and NEVER get this problem back. When I had this problem, my cpu would restart like 15 times a day, so better not use it.
Anyway, I entered Ubuntu again with the USB cable and typed "ifconfig". I got the following words:
" ubuntu@ubuntu:~$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:191:02:95:75
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Base address:0x20c0 Memory:52200000-52220000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:96 errors:0 dropped:0 overruns:0 frame:0
TX packets:96 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:7120 (6.9 KB) TX bytes:7120 (6.9 KB) "
If I can't have internet via USB with Ubuntu, then I sadly give up. Please tell me if the ifconfig command has some utility here, thanks.

Use the ps/2 plugs for mouse and keyboard.
Failing that, add "irqpoll" to your kernel line.

ifconfig is detecting your ethernet card and loopback interface. Use lsusb to see your modem.
Still waiting for model.

That tutorial you followed says:
USB Modem will not work with the Ubuntu live CD.

I tried lsusb and I got :
Bus 006 Device 001: ID 0000:0000
Bus 007 Device 001: ID 0000:0000
Bus 004 Device 001: ID 0000:0000
Bus 001 Device 001: ID 0000:0000
Bus 002 Device 001: ID 0000:0000
Bus 003 Device 003: ID 1110:5c01 Analog Device Canada, Ltd (Allied Telesyn)
Bus 003 Device 001: ID 0000:0000
Bus 005 Device 001: ID 0000:0000

I have a question : If I buy a new disk and I install Ubuntu on it, will I be able to connect (using my modem via usb) to internet without passing by configuring my internet connection?
As I would like to have a dual (windows xp/Ubuntu) computer, I prefer to use the usb port for my modem. I hope it is possible with Ubuntu when fully installed on my hard drive.