Go to CentOS page and install the RPMForge plugin.
yum install dkms-ipw3945
lsmod |grep ipw
Done..the wireless card is detected but still cant seem to get the wireless network. After some more digging, found that the ipw3945 project has been deprecated and superseded by Iwlwifi at http://intellinuxwireless.org
Below are notes to try, but I have yet to find the apps that is talk to the wifi daemon that connects to the wireless network.
The ATRpms repository contains Iwlwifi. Plugin to the wired network. Edit the repo file with
name=EL $releasever - $basearch - ATrpms
Since gpgcheck is enabled, run the command
rpm --import http://ATrpms.net/RPM-GPG-KEY.atrpms
Install the drivers
yum install iwlwifi iwlwifi-kmdl-`uname -r`