I have a HP Pavilion P7-1235 with the onboard Atheros Communications Inc. AR8161 Gigabit Ethernet (rev 08) card. It was not recognized by CentOS 6.3.
Did some research and purchased an Intel Corporation 82574L Gigabit Network card.
NewEgg lists it as "Intel EXPI9301CTBLK Network Adapter 10/ 100/ 1000Mbps PCI-Express 1 x RJ45" at http://www.newegg.com/Product/Product.aspx?Item=N82E16833106033.
The card was automatically detected by CentOS6.3 upon a fresh installation from CDROM. It did not need any special drivers, even though Intel makes them available. I did have to go into system-config-network and setup the gateway, dns, etc. I also had to edit the /etc/sysconfig/network-scripts/ifcfg-eth1 file and set ONBOOT=yes to activate the device.
Intel has a support page at http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=15817&ProdId=3025&lang=eng&OSVersion=Linux*&DownloadType=
Update 18 Sept 2014
Earlier this week the network card disconnected randomly and a full reboot was needed for it to reinitilize itself. Google search seemed to indicate a problem with this particular card being prone to random disconnects. So I revisited the Onboard NIC as noted above not having a driver, and there is one availablel through the ElRepo linux repository.
Install the ELRepo respository from http://elrepo.org/tiki/tiki-index.php
yum -y install kmod-alx (version installed was kmod-alx-0.0-8.el6.elrepo.x86_64)
Reboot; NIC should be found automatically. Configure as needed via NetworkConnection Manager.