Networking, not

You will need to purchase some form of network device to allow both the desktop and the laptop to share the connection over the cable modem.

The only way to not have to do this is to purchase a long (50') patch cable and run it into the other room. Then when you wish to use the laptop, you plug that cable into the modem. When you want to use the desktop you plug the cable you're using now into the modem.

edit: clarity

To use a NB you only need a WiFi Access point if you want to jump on the Internet or collect your Mail.

As stated above run a patch lead to the other room where you want to use the NB and change the cable and cycle the Modem through a power off and on cycle after unplugging the Desktop. Of course a Switch between the Modem and computers would also cure this problem or a WiFi Access Point not a WiFi Router is required. Currently with all new Cable installations the ISP's here provide a WiFi Gateway Device to the new clients with no security enabled so that it is possible to steal the Internet Connection and gain access tot he computers connected to the Modem if you know what you are doing.

Col

You could do what I have done on my home
network. With 5 machines and cable modem my
son and I took an old P2 machine and using
linux made it into a firewall - router. The
first thing to do is install 2 network
cards in the old machine you plan to use as
the firewall then install linux onto this
machine, in our case we used Mandrake 9.2
as this was a low spec by today's standards
machine and this distro was an excellent
match with this hardware.

Then you configure one ethernet card to the
IP address of your cable modem which will
enable this "gateway" machine to be
connected to the internet. To keep things
as simple as possible we configured all of
the other machines on a private network
with fixed IP addresses (192.168.0.1-to 255
subnet 255.255.255.0) just basic class C
private network this way we did not need
our own internal DNS server. We purchased a
network hub for small change from a
technology recycling centre. Then using IP
tables which comes with linux we configured
the linux machine as a gateway to the
internet to translate the internal IP
addresses to the single IP address of the
cable modem.

When we first went onto the cable modem my
son had already built the internal network
as his friends would bring their machines
around to play network games. We had dial
up at this time and when anyone wanted to
use internet they would just run a long
phone cable to the machine they were using.

We upgraded to cable. The tech who came to
install cable modem has no idea of how his
system worked and my son had to work out
how to get even one machine connected for
him. With XP he was unsure and with the
linux machines he was even more confused
the big problem he did not know basically
any theory of how cable modems connect to
internet yet he was installing them. In our
ignorance at the time we plugged cable from
modem strait into our hub which after a
small amount of research we leaned that
this was not a good idea and ISP's don't
want you do do this to their network,
something this "tech" didn't mind us doing.

With a bit of help from Google we were able
to find out how to set up connecting
multiple machines to one cable modem. The
Linux "IP Tables howto" which we downloaded
from net gave us all info we needed to get
up and running (we used basic config file
in this document to get up and running). As
we have learned a little more we have made
a better firewall - gateway config.

There is a bit of work initially going this
way, more so than just purchasing hardware
to do this all for you, but as I see it
there are many advantages as well. Firstly
this is a cheap solution, gateway computer
was a " throw away " and was free, the hub
and cables etc would be less than $50.00.
The biggest gain from going this way would
deffinately be learning a lot of usefull
knowledge, especially for my son who is
only 16. Since building up home network and
connecting to internet though gateway he
has gained some very markitable skills. He
made all cables himself, wired house very
professionally with plugs in each room and
cabling run under floor, built Linux based
game servers to run games like "Call of
Duty" and "Half Life" he has learned how to
use IP tables to filter web content. and as
an old boss use to say when I was starting
out in my career, "its a good day when you
learn something new"

As hub sits in a corner of lounge if I want
to use my laptop on internet I just plug a
cable in. My daughter will bring her laptop
when she comes over and plug in to hub.

(edit sorry for strange formating but
whenever I use Konqueror on Tech Republic
it always comes out this way- If any of you
Linux guru's can tell me how to fix this
I'd be thankfull)

There is a setting in most cable modems (that you probably don't have access to) that allows traffic from ONE mac address (MAC=Media Access Control). There is a unique 12 digit hex number on every ethernet port in the world.
If you cycle power (unplug/replug the power cord) on the cable modem when you switch computers, you should be okay. Its generally a good idea to hide your PC's behind a hardware NAT'ing (Network Address Translation) firewall/Router any time you are on the internet, to avoid PC security problems. NAT'ing router will allow multiple PCs to connect using the MAC address of the router.

I hope that this helps.