Mark,
Thanks for posting the details, that helps us get a visual of what you would like to achieve and definitely helps in making sound decisions.
Since you have multi-level home, bluetooth won't work very well. Bluetooth has a limited range (At best 15ft) and the farther away the lower the signal strength.
If you are looking into a wireless solution I recommend going with an 802.11g setup, it is faster than the 802.11b standard BUT it is also compatible with 802.11b so you can use both if you have to.
Also, since you are going to have a broadband ISP you will want to get the Wireless DSL/Cable Router, that will share your internet connection between computers AND allow you to have wireless capabilities! There are many brands out there, personally I have the Linksys
WRT54G and it has been working GREAT for me! The router also has 4 ethernet ports so I can directly connect computers to it if I want to! Bear in mind that you will have to get a few things to get you up and running.
You will need the following:
1) Wireless Router
2) Wireless Network Card (For everycomputer in your network, except the computer that will have the DSL Modem)
3)Some common sense and patience.
The reason you don't need a wireless network card on the computer that the modem is connected to is because you can connect that computer directly to one of the ports on the switch.
If you want more information on Wireless networks click
here.
For information on router solutions click
here.
If you have anymore questions let us know!