You’re happy with your Ethernet-based LAN in general, and all you’d like to do is add a wireless laptop to it. Do you have to spring for the big bucks and buy an Access Point to connect it in?
The answer is No, but you may want to anyway. The explanation follows…
An Access Point acts as a bridge, connecting whatever is on either side of it into the same subnet. In simple terms, this means that not only will you be able to access Internet services (assuming you’ve already got some sort of Internet sharing set up on your Ethernet LAN), but File and Printer sharing will also work.
If you go the cheaper route, you’ll need to install a wireless card into a desktop machine on your LAN, then install some sort of sharing software like ICS, Wingate, Sygate, etc. on that machine. All these products, however, are routers, not bridges. They will put your wireless client into its own subnet and although Internet services should work just fine, you won’t be able to File and Printer share unless you set up LMHOST files on all machines on your network. Even then, the Network Neighborhood (or Network Places) browser won’t automatically find the machines on different subnets. This is explained more on this page from our MMR HowTo.
So, easier and more expensive, or harder and cheaper. In this case you really do pays your money and takes your choice!