YABQ (Yet Another Beginner's Question?) - Wifi between Mac and XPwith PCI ADSL modem

Box1:

Connexant PCI ADSL Modem
XP

Box2:

Airport Extreme (g)
Apple G4 ibook Laptop

I am new to wireless but would like to to do the obvious thing - link
them up and have Box2 use Box1's connection.

From all I can gather I should get a WAP and a PCI wireless card for
PCI and estabilish a wifi network by means of box 1 and the wap to which
box2 would then connect.

My question is: since I only need to connect these two machines can I do
without the WAP and only with a wireless card? The concern is not so
much price but also trying not to have boxes around. So failing the
above, are there any wap points that live inside pci cards?

Any help much appreciated.



Alex