I work for a small computer shop and a client brought in 6 older Dells to be reformatted and donated to a church. I formatted them and reinstalled Vista on them and the first 5 went like a charm, though had to manually install the Intel network driver to access the internet. The last one however says that it does not have Intel Network Connections when I try to install the driver and nothing appears in device manager about the ethernet controller. I have reformatted multiple times, re-installed chip-set, and tried every other network driver from Dell's service tag to no avail.
Dumb question, is the network card enabled in the bios? In the setup (when machine boots, press F2 or ESC or whatever the screen prompts) check around for something like this;http://philipyip.files.wordpress.com/2014/07/bios-nic.png