setting up Wireless Security/access for a WRT54GL?

h'lo all, hoping to get some advise on setting up my new WRT54GL.
this is my first encounter with a wireless router, though I've had 3 previous Linksys (hardwired) routers.
I have to say, given that they give virtually no Mac support, it was a breeze….just plugged it in to my cable modem and my laptop and - boom - on the net on my first try!

I'm able to access the router via it's web-based system and can now "tweak" with settings, but I'm running in to a lot of "tweakable" settings that I'm not familiar with and that makes me nervous! hence my post here for help… I don't *think* what I hope to accomplish is all that difficult, but perhaps you can tell me.

First my setup. I have; (a.) 3 desktop Macs and a Samsung TV hardwired to the four Ethernet ports and (b.) my Mac laptop accessing the router via Airport Extreme wifi. All are happily accessing the web.

But I realize that the reason that "(b.)" is accessing the web is that I've changed no default settings in the router and, not only can *I* access the router via wifi, but probably anyone driving down the road or sitting out in front of my house can access the web via my wifi. And I'd like to change that.

I'm *guessing* that the router settings i need to change lie in the "Wireless Security" area of the router? And it's here that I'm running in to a lot of "tweakable" settings that I don't understand.

But let me give an example of what I would *like* to accomplish. And, for my own understanding, I'm going to keep it extremely simple.
Let's say that there are 3 different laptops…."A", "B" and "C". All 3 are Macs and running Airport Extreme.
Now, "A" is my laptop, sitting here on my desk next to the router. As i leave Airport always turned on, I want "A" to *always* have access to the routers wifi *without* having to enter a username/password, i.e. when i turn "A" on, it's wired.
Now "B" might be the laptop of a friend who happens by the house and need access. They would need to find my network on their laptop and then i would need to give them a password to let them get on .
And finally, "C" is the guy I don't know out in the street whom I want to *never* have access to my network.

So my question then is, can I accomplish this by changing settings in "Wireless Security" on my router and how/what would I change?

 

miles, can't thank you enough! your description was spot on and it was a snap to setup. thanks again and I'll be back!