Hey man,
If you are talking about setting up a home network with shared internet connection:
Make the desktop the 'server' because you will be needing two NIC's (Network Interface cards) in the 'server'. The NIC's for laptops are more expensive then the PCI one's used in desktops.
You need to connect one NIC form your server to the cable modem. The other NIC needs to be connected to your laptop.
The cable to the cable modem needs to be straight utp cable, the cable between the two computers needs to be a crossed cable.
Does your cable modem have a DHCP server built in? Do you know what IP has the cable modem? It probably be something like 192.168.0.1... Or is it a USB cable modem?
If your modem is connected via an UTP cable then configure your server as follows:
NIC Connected to modem:
IP addr: 192.168.0.2 [ONLY IF your modem has 192.168.0.1 as IP]
Subnet mask: 255.255.0.0 [or same as your modem's]
Default Gateway: IP addr of your modem
DNS servers: your ISP's DNS Servers
NIC Connected to the laptop:
IP addr: 10.0.0.1
Subnet Mask: 255.0.0.0
Default gateway:
DNS:
NIC in the laptop:
IP Addr: 10.0.0.2
Subnet mask: 255.0.0.0
Default gateway: 10.0.0.1
DNS Servers: ISP's DNS Servers
On the server you need to enable ICS (Internet connection sharing)
You need both pc's to be in the same workgroup, but have different computer names.
You could also use the Windows XP wizard to configure both pc's.
Also, have a look @
http://www.homenethelp.com/sharing/cable-modem.asp
or
http://www.practicallynetworked.com/sharing/xp_ics/
And try google for other tutorials.