Configuring a Windows XP Client
Windows users will require the WPA2 patch, if it's not already installed. A quick way to check for this is to open up the advanced properties on any wireless network. If WPA2 is not an option available from the Network Authentication dropdown, you need the patch.
After installing the patch, transfer the CA certificate and the p12 file containing the client certificate and key securely from the server (via a USB flash drive is the easiest).
First, install the CA certificate as a trusted authority by double-clicking on it.
Figure 3: Installing the CA
Click "Install Certificate" and complete the wizard. Next, double-click on the p12 file that contains the client certificate and key to install it.
Figure 4: Installing the Client Keys
Enter the password for the client's private key. (You can optionally require that the password is entered everytime the key is used, this gets annoying real quick, so I usually leave that unchecked.)
Figure 5: Client Password
Let Windows automatically store the certificate where it thinks it should go.