I concur with James W.
My situation is that my ISP provides me a WiFi/wired router. The router is upstairs, near my wife's workstation. My work area is two floors below - no option to pull Cat5/6 cables from the router to my workstation. I have a Mac mini OS X 10.5 (which has a built-in WiFi adapter and a built-in wired ethernet adpater and a two PCs in my work area, both with built-in wired ethernet, but no WiFi adapters. I also have a mini-switch for wired ethernet.
My only solution (without buying more hardware -- which goes against my cheap-a__ bastard grain) for connecting my work area to the internet is to use the WiFi connection that my Mac gives me. The question then becomes: what option should I choose for extending that connection to the pair of PCs?
The obvious answer is to use Mac's nice little Internet Connection Sharing (ICS) function. However, I run a bit torrent client on one of my PCs, which I wish to make available to the internet via port-forwarding through my ISP router -- it's how you "pay back" for the benefit that I'm reaping, right, citizens? This means that simple ICS won't do the trick, since I would then need to port-forward through my Mac as well (which, incidentally, I have a difficult time learning how to do, even when consulting Google to tap y'all's smart brians).
An elegant solution would be to bridge the connection through the Mac, right? So that my PC is on the same network as the ISP router (whose port-forwarding functions are built-in and easily managed).
How to do it? As James W says, is it true that there' a sole solution (which costs $100)? Say it ain't so, Joe!