What to think about:
From wet dream to reality in a few short years. That's the story of wireless networking. Two years ago, this was uncharted and expensive territory. Now, it's possible to get on board for less than a bill. I am not going to attempt to fill you in on the whole story here, as there is an incredible amount of great info on the web. Rather than bore you with a regurgitation, I will point you in the right direction. Unlike most technology that creeps up on us, this is pretty much a no brainer. There are three types of wireless that a consumer will run across: 802.11b and 802.11g (collectively known as wifi) and Bluetooth.
In short, wifi is a faster protocol (802.11b runs 11Mbps while 802.11g runs 54Mbps.) The current claims are that wifi will reach out around 300ft indoors and 1000ft outdoors. I have not tested these claims other than to be able to tell you that I can get coverage anywhere on my property (a midwestern tract home.)
On the other hand, Bluetooth was set up to connect smaller and less power hungry devices up over smaller distances. It is a slower and tighter protocol which covers somewhere in the neighborhood of 30ft. Rather than hardcore networking, it was designed to allow for smaller wireless devices such as cell phone headsets, cell phone to car stereo links, etc.
Since they are all either standard protocols or work with standard protocols, you can use them on any operating system you might come across. My house has both Windows and Linux machines, along with a Linux PDA, and everything works like a dream. Needless to say, I left out alot. Most of the stuff I left out doesn't matter (other than learning how to secure your access point.) For a more thorough treatment, check out the links on the bottom of this page.
Hardware you will need:
There is not a whole lot of hardware to worry about. In essence, you will be replacing some of your current hardware with wireless version of the same:
Router: You will need a wireless router. See the links on the bottom of this article for hella deals on this stuff. Expect to spend a little less than you initially spent for the wired version of your router. There are several variants on the (g) standard, but none of these have been settled on yet. If you pick up a (g) standard router, you will be golden.
Interface: You most likely use a network interface card to get on the net now. You have a choice of either picking up a wireless interface card, or a wireless usb adapter. Whichever standard you want to choose is fine, but remember, if your computer is older, and you have only usb 1.1 (or even 1.0) you will have a pretty much unusable connection to the rest of your network.
For your PDA, you will need to pick up a wireless adapter for its interface. Expect to pay in the neighborhood of $50.
What I use:
I have been using some very standard gear. For my wireless router, I have been using a D-Link DI-524. To tell you the truth, I don't know much about it. I plugged it in, set it up for my servers, secured it, and it has been running steadily ever since. Ten minutes of setup time, and it has run flawlessly.
Currently, my desktop systems are hardwired to my network. I have yet to add wireless cards to them, but I will be next week, as I have one wire that has been dragging around on the floor driving me nuts.
As for all my PDA and mobile equipment, I have found that the SMC EZ Connect is available CHEAP (I have seen them as refurbs for $16) works like mad. With all this gear, I spent just a few minutes setting them up, and they have run like raped apes ever since.
A pretty simple and straightforward tutorial that includes security and access points.
This is a D-Link centric tutorial that gives a broad overview with some nice pictures of gear.
If you just can't get enough jargon and charts, check this out. It's actually a good overview on security, too.
If you have made it this far, you know everything you need to know to set up a secured wireless access point, and could probably make some money selling access to your buddies.
Tiger Direct's intro to Bluetooth. Spend the ten minutes reading this to get a feel for Bluetooth.
This is always a good place to start shopping for wireless gear. This link goes directly to the wireless department.
Another source for good networking gear on the cheap.