as talked about before, there are few ways of doing it, 2 main 1ns being a router or using a crossover cable and xp connection sharing.

Router notes:
- routers can be quite expencive, but the price comes down fast when you loose features such as wireless and being able to plug more than 4 computers into them.

- routers are allways on, so you can use the internet even if yours is the only computer turned on

- routers can be a bitch when it comes to config, but with "modern" routers, they pretty much set themselfs up now

- going wireless is a real "option" for you to take with modern routers, they have strong encryption (remember this will need to be setup and configured), and good connections (shame we are locked down in the UK signal strength wise, in the us they have massive signals). like all methods of communication it CAN be broken and your router "cracked", but with the ammount of packets sent over the router with 2 computers it would probably take months. the only downside to wireless is the price involved, it is the "new" way to network, so wireless router prices are up, i payed 150 for mine, and a standard pci wireless card is around 50. (try not to get usb adapters as they have lower power and cant go as far)

xp Sharing notes:

- internet connection sharing is only on XP Pro Edition

- the "server" computer (one with the modem) will need to be turned on for the other computer to use the internet

- i have only managed to get it working once. it worked fine once it got started, i'll give it that, but, it wouldent surprise me if you ran into so problems with it.

- software firewalls installed on the server computer will effect the connection sharing, xpfirewall and any others. with "good" firewalls you will have to set them to work in "gateway" mode - this will disable stuff that hides ports so people can connect to the other computer "through" you ok.

blablabla
yea...

lots of things you can do
but you probably just wanted me to say:
cheap and fastest option would be to -
get a cheap 4port wired adsl router with modem, 2 cat5 network cables long enough to connect them and thats it (other than router config).