My Network Puzzle!

ok, here goes.
i'm trying to configure my network and i'm having a few problems.

i have 3 computers. A, B, and C.

Computer {A}
is the main computer, it has 2 network adapters and sits near the cable modem. its the most powerfull pc, and is always on.

Computer {B}
the kid's computer, much older, sits in far room, and has a PCI WiFi 802.11G card installed.

Computer [C]
Notebook computer, has WiFi of course.

now, the problem is i do not have a router. what i do have is an access point. so what i was thinking was this:

Computer [A] will connect from one lan adapter to the cable modem and gain internet access (which it does, right now)
and from the 2nd Lan adapter it will connect to the Access point and spread the internet access to the two other computers connected via Wifi.

this is all nice enough in theory but i can't seem to make it work. the farthest i got is having computer [A] connect to the internet and having computers {B} and [C] connect to computer [A] for file sharing and ping access.
i even managed to establish a home network, share a printer... but NO INTERNET ACCESS is being shared.

i tried "Bridging" the two lan cards,
i tried the microsoft Internet sharing,
but nothing works.

can anybody help me with this?
how can i make it work? any certain ip address that needs to be issued? any online guides out there that could help me?

thank you !