Can not connect to the Internet because you are missing your Windows PCI bridge controller? You can go into "Control Panel" and then "Device Manager". Right click on that PCI bridge controller and delete it.
Click on a refresh hardware list icon in Device Manager. Windows will find that PCI bridge again. You might be asked for installation media.
If you have a restore CD or a Windows XP CD place that into your CD-ROM drive before you reinstall that PCI bridge. It should copy that needed driver off that CD. Another option, is to perform a system restore back to before this issue occurred.
Go to "Control Panel", then select "System", and then choose "Restore". This following fix worked on an Emachines T6426 running Windows XP.