You don't need a certificate, but if you want to know more, read on.
Wireless network security is effected by use of encryption. In order to
decrypt the encrypted messages, each side of the communication link
(client computer and wireless access point) needs the correct encryption
key.
Today, the best available wireless network encryption standard is known
as "Wi-Fi Protected Access 2" or WPA2. An older but still effective
standard is WPA. The first such standard, Wireless Equivalent Privacy
(WEP) is no longer effective, because it is easily cracked using readily
available tools (this was originally thought to be "equivalent" to a
wired network).
In a typical home or small business wireless network, the encryption key
is "pre-shared" which simply means that after the key is set in the
access point, it is manually transferred to each client computer and
manually stored there. This can be done by writing the key down on a
piece of paper (or just remembering it) or by using something like a USB
flash drive. Because the key is pre-shared in this way, there is the
possibility of some security compromise. This type of encryption is
called WPA2-PSK or WPA-PSK. Sometimes, instead of "PSK" (pre-shared
key), it's called "personal," as in "WPA2-Personal."
In larger businesses, a more secure system is used. This is known as
802.1x, which is the name of the standard adopted by the IEEE. In this
system, the client must present its "credentials" to an "authenticator"
and be "authenticated" before any substantive communication with the
client is permitted. Usually, the wireless access point forwards the
credentials of the connection attempt to a separate authentication
server. Typically, a wireless AP uses the Remote Authentication Dial-In
User Service (RADIUS) protocol to send a connection request message to a
RADIUS server.
In a sequence of back and forth communications known as a "handshake,"
the RADIUS server authenticates the wireless client's credentials. Once
it is satisfied, it sends encryption keys (which themselves are
encrypted using information from the handshake communications) to the
wireless client, which then uses those keys for the remainder of the
session.
One type of credential that may be (and very commonly is) used in the
above system is known as a "digital certificate." A certificate is
obtained from a Certification Authority (CA), which may be a server on
the network or it may be a commercial entity. The certificate is a
"guarantee" by the CA that the public encryption key contained in the
certificate actually belongs to the person (or computer) named in the
certificate.
All of this is a rather long-winded way of saying that a certificate, in
the context of wi-fi security, is only used in connection with an
authentication server, such as a RADIUS server. Because there is no
RADIUS server in your system (if there was, you would know all of the
above and more), you don't need a certificate. More importantly, if you
were to check the box to "Enable IEEE 802.1x authentication for this
network," which is on the "Authentication" tab of the "Properties"
dialog for your wireless network connection, you would be informing your
wireless access point to start the credential authentication handshake
process described above. This process would immediately fail, resulting
in a "Windows in unable to find a certificate to log on to the network"
or similar authentication failure error message.
If you are really masochistic and want to know more, see
http://technet.microsoft.com/en-us/library/bb457016.aspx and/or
http://www.microsoft.com/downloads/...48-74ec-4ee8-a650-334bb8ec38a9&displaylang=en
