New powerbook as airport base station

[Tom Seid]

Just wondering....under the 'old' airport, I remember being able to hook up
my iMac a couple years ago and using it as a base station, and therefore,
not needing an actual base station...is it still possible to do that under
airport extreme, or do you need an actual base station?....I just bought a
new AlBook with an eMac (both with extreme cards) and I am trying to
replicate that without shelling out $200 for an additional station...
Thanks
Tom