would distribute the broadband connection to any computer, anywhere in range. That means that you would be able to have more than one machine sharing the connection if that's what you wanted.
The distribution range will be affected by intervening walls and staircases, and it isn't possible to give any hard and fast guidelines. My own home wireless network uses a Linksys WAP 11 2.4GHz 802.11b wireless access point, and it provides coverage throughout the house and into the garden. There are reception anomalies however, and I can't access the broadband connection in the kitchen - not a big deal, that!