Do you even need a Wi-Fi Router?
Before you spend $50 on a Wi-Fi router, there is something to consider: do you even need one? If your entire network is running on wires, and it works fine, then you don't need a Wi-Fi router. If all your computers though are in one spot, and you really wish to migrate, you may consider Wi-Fi. But remember, if you buy a Wi-Fi router, you better milk it's money's worth. Buying a $50 for a router to accompany your DS is like buying a $50 accessory for it. Also if there's only like one computer that will use the Wi-Fi access, it's not worth it either. For video game consoles, notably Nintendo's, you're better off buying the USB Wi-Fi adapter or just hooking it up to your network via wire.
Also note that if you plan on upgrading to Wi-Fi, remember that ALL DESKTOPS NEED AN UPGRADE AS WELL. Most desktops don't come with integrated Wi-Fi receivers, and receivers are just about as expensive as the routers themselves.
What do I need to get online?
1. A compatible Wi-Fi router (or access point adapter).
2. Broadband internet (basically DSL or cable)
3. Windows XP with Service Pack 2, Windows Vista, or Mac OS X in order to use Wi-Fi without third party software.
How can I even access Wi-Fi?
There are two things to understand. With Wi-Fi there are two kinds of equipment, a receiver, and a access point. An access point is where you connect your Wi-Fi enabled equipment to, which those are called receivers. Sometimes equipment can be both receivers and access points, under what is called ad-hoc network (this is how the PSP and DS communicate with each other). When you're shopping for Wi-Fi equipment, make sure you're getting an access point creator (which is a router) or something that can create an ad-hoc network. However, the trouble with ad-hoc networking is that you may have to be in close proximity.
How to access Nintendo Wi-Fi or some other network
For every Wi-Fi enabled system, you can use an approved Wi-Fi enabled router. Most modern models will do, namely from Netgear or Linksys. Those that don't have built-in Wi-Fi will either have a first party attachment (such as for the Xbox 360), or a third party attachment (for older consoles). Nintendo specifically has a USB adapter that acts like an access point for just the Wii and DS.
Remember to follow all instructions when installing equipment. Also all systems of the current generation use both 802.11b and 802.11g.
Using Wi-Fi access points in "free" access places.
The only place with true "free" Wi-Fi access is any public place, that is if it's government owned. However, some of the government owned places also have requirements. For example: to use it when in the library, you might have to have a card. To use the wi-fi at a school, you must be enrolled in it.
Using Wi-Fi at a commercial establishment like StarBucks or McDonald's is only allowed when you've purchased something. Depending on the establishment, you'll get away half the time, but you can be pressed charges on the account of resource theft, which is pretty much the same as any sort of theft.
Maximum Range of Wi-Fi
The maximum range of Wi-Fi is typically 250 feet in an open space. The optimal range is 100 feet in an open space. When you're looking at a closed space like your home, those figures drop to about 125 feet maximum and 50 feet optimal.
Maximum range means how much you can get one bar. Optimal is typically around three bars. You need to be within 20 feet of the access point to have full bars.
Settings to keep things simple.
This is from my NETGEAR router, so settings may vary.
Does your Internet Service Provider (ISP) require a login? Should be set to "No" unless you really need to log in. I believe by setting this to "Yes" and filling out the required information will allow your router to automatically log on to the internet. If you don't set this up, there's a good chance your DS will not connect.
Account and Domain name: Only applicable if you connect to a server based network (that is, you work in the professional setting). So leave it alone
Internet IP address: Set it to "Automatically Obtain IP Address", or in the case with NETGEAR, "Get Dynamically from ISP"
Domain Server Name (DSN) Address: Set it to Automatically obtain, or "Get automatically from ISP"
Router MAC address: Set this to Default or Get Automatically.
SSID: This is the name of your network. By default it's usually the router's model name (so change it to something you'll know).
Region: This is locked for me. Otherwise, set it to the appropriate region you live in.
Channel: Leave this alone. If you are noticing connection conflicts (such as another router is within your area), changing this may help.
Mode: Leave this on Auto.
Security Options: After a little investigation, I realized that WEP is weaker than WPA. Your best bet is to use WPA+WPA2. Either one works though. However considering the DS asks for a WEP key, you might have to set this to WEP.
Passphrase (WEP): For WEP you need to set two things. First is the strength. For maximum strength, use 128-bit encryption on an automatic type. Second is the passprhase. Just type up something you can remember. This acts as a primary password which generates a set of keys. The next thing you have to do set which key you want to use. The key is what's you need to write down.
Passphrase (WPA): WPA is easier, you just enter a passphrase you can remember.
When you set up your DS for the Nintendo Wi-Fi Connection, make sure all the options in it matches what you set in the router.
Finding your WPA or WEP key
1. I'm going to assume that either you're the network manager, or nobody gives a penny about who manages the network.
2. If there is a network manager and you're not it, then ask that person first.
So how to find your WPA or WEP key:
If you are using a recent Netgear Model, going www.routerlogin.com will get you into the firmware, otherwise use this:
1. Go to Start -> Control Panel -> Internet and Network Connections -> Network Connections.
2. Double click on the "Wireless Network Connection".
3. Click on the "Support Tab", and note what your Default Gateway address is (it should start with 192.168.1)
4. Type the address up into an internet browser.
5. On the login prompt, use username admin and password password. This is the default setting. If this was changed at any point, ask your network manager for login information.
6. Find your router's wireless settings. The WPA or WEP key should be in there. If not, look for wireless security options.
7. If there are multiple keys, use the one that's selected.