One if the latest things to hit home networking is WiFi (802.11b). It's got almost the same bandwidth and the average hub (11MB vs. 10MB of a hub) and lets you put networked computers almost anywhere.
But there's the hidden gotcha - securing it. So often users bring home a new cable modem router that has WiFi on it - whether they are going to use it or not - and it is left on and unsecured, meaning they have not set up a 64 or 128 bit key or passcode to protect if from bandwidth theft. Some stores even set up WiFi points for demonstration purposes - and shoppers that have WiFi devices can surf the Internet unknown to the folks in the computer department. Kind neighbors that leave their access points open just started a free WiFi provider service. People that go for walks nearby can check their e-mail over their WiFi handhelds since most units have a about hundred foot range coming from the inside of a house out to the street.
People, if you're going to get a new router for your cable modem - take 5 minutes to go through the manual and set a key on the WiFi so people can't just stumble into your network. If your neighbors can check their mail - spammers can send mail - it it really would have come from your computer - or at least your router. We all know how ISPs are about saying that kind of thing still makes it your fault since you didn't properly secure your network.
They simply have to wander into a neighborhood and probe for networks, once they find one, they can just willy nilly send messages out. If you will take that extra 5 minutes you might just help squash out some of those spammers. You can have your firewall, and that will protect you for the most part from users that are trying to get in from over the Internet - but if they are just hooking into your network as if you let them run a patch cable out to their computer, it doesn't matter that there's a firewall in place - they're already in. Another, but less effective method, is only allow certain IP addresses to get through to the Internet or only use static IPs within your network since getting DNS servers and the like will be harder for the prospective hacker.
If you don't even know what wireless networking is, and you just bought a wireless capable unit (one that has antennae), you probably wasted a good $50 on a feature you won't be using. For users that still want a router/firewall for their cable modem/DSL connection, a unit without WiFi will cost less and you won't have to go through locking down an unused feature.
I've been running wireless networking for about a year. I've found it to be very handy - I don't have to run cables everywhere just to surf the web from wherever I want. I initially began my network with a linux gateway, but then migrated to an out-of-the-box gateway/router, a Linksys BEFSR11. These were used in conjunction with several Netgear hubs. I got a Netgear ME102 on clearance when I wanted to go wireless, it was easy to configure. Once I flashed with a downloadable update, it supported 128 bit encryption, for which I set a strong key (meaning somewhat random series of hex values not a pattern like aabbcc112233... but closer to 7a543c879c6f..).
I've used Belkin and Netgear wireless PCMCIA cards with it and have found that they are very similar to each other to configure - just fill in the same values you did for the access point and you should connect right up. 128 is better than 64 bit in the sense that there are twice as many characters that some one would have to guess in order to come up with the right code - just like using an 8 character password is generally more secure than a 6 character password.