please help me with setting up a home network

Greetings people

long time since I havent posted in these forums

I have a problem
I bought a laptop a month ago and I want to make a network between the laptop and the desktop
I dont have 2 cards, so it the network will NOT be linked to the internet
the desktop will be either linked to the internet or linked with the laptop, ( depending on what I want at the moment ), BUT NOT at the same time.

my PC knowledge is good regarding the building of PCs, have made about a douzin so far for me and for my friends, and also have a good experience with OCing, but when it comes to networking I am clueless.

I have read about how to setup a network but usually all the articles and all the advisors from the forums think you know what you are doing, and frankly there are quite a lot people like me which have absolutely no idea of what they are doing, so the advice must be given in the form of step by step, like teaching a 7 years old how to write.

my configurations:

desktop
6600 quad, gigabyte DS3 MB, 2 gigs ram vitesta xtreme edition, Asus 6600GT, 320 GB seagate, Windows XP profesional 32 bit

laptop
Thinkpad R61i with core 2 duo E5250, 1 gig ram, 120 GB hard, intel X3100, Windows vista business 32 bit

I have the crossover cable
I just need to know how to setup the 2 comps
BUT PLEASE, step by step advice, like for dumb people

well, I am not willing to drop this one yet, am saving the router idea as a last resort.

I did that already and it didnt work ((((