You've got an older laptop, and you want to connect it to the internet, or your laptop has an older wireless adapter that doesn't support new network speeds.  What can you do?  The solution to this problem is a USB wireless network adapter.  These adapters, often called "dongles," allow you to connect to a wireless network without having to gut your laptop and try to install an internal card (which isn't always possible).  Instead of sitting inside your laptop, these adapters fit inside a free USB port on your machine.  They can also work well with desktop computer.  If you do get one, make sure you will have enough free USB ports to use the adapter.

The adapters are available at all different networks speeds, allowing you to connect to the latest wireless N networks for the maximum connection speeds.  This is great for those with older laptops who want to step up to higher speed wireless networks. 

A couple caveats when it comes to these wireless dongles.  Since they sit on the outside of your computer, they can be prone to snapping off if you don't watch out for them.  Be careful when handling your computer with the USB adapter attached.  Another factor to consider is the placement of the dongle for the best reception.  Typically, you want to avoid placing these on the rear of the computer, but rather somewhere on the side.  This placement allows for the best possible wireless reception.

If you are a Linux user, be sure to do some research and see if the USB adapter you want has solid Linux drivers.  USB wireless adapters are not always as well supported in Linux as their PCI brethren.  Just something to watch out for.

You can purchase USB dongles at your local electronics store or online.  As always, purchasing online gives you the greatest possible selection while allowing you to save money as well.  However, USB adapters are quite affordable these days, so this might not be a big deal.  When shopping, try to find a smaller model, since these will be less likely to get knocked off by clumsy handling. 

In short, buying an external wireless adapter isn't that hard.  Just find a model that looks like a good fit for you, and start enjoying wi fi on your computer.