Most home wireless networks are implemented using a wireless router. The
typical SOHO wireless router has 4 LAN jacks in addition to its wireless
access point.
Thus, you can add a second desktop to the network either by connecting an
Ethernet cable between an Ethernet NIC in the desktop (most desktops have
one of these) or by installing a wireless NIC (most desktops do not come
with these).
The wireless NIC can be internal (PCI card) or external. External
wireless adapters are typically USB. They may either be something that
looks like a flash drive (which I don't recommend because of antenna
placement) or a separate box with a USB cable. The latter is a good idea
because you can position the box and its antenna out from behind the case
(which often is stuffed under a desk).
For example only:
wireless PCI adapter:
http://tinyurl.com/6o9ae7
wireless USB dongle:
http://tinyurl.com/6pdg5h
wireless USB adapter:
http://tinyurl.com/6agwt9
--
Lem -- MS-MVP
To the moon and back with 2K words of RAM and 36K words of ROM.
http://en.wikipedia.org/wiki/Apollo_Guidance_Computer
http://history.nasa.gov/afj/compessay.htm