After reformatting your drive, and reinstalling XP, your computer has no information from your previous installation stored on that drive. You will need drivers for everything. Motherboard, video, audio, and network are priority. If you do not know what parts your system has, look up your model number of your computer if it's prebuilt. If you have a custom system, you should be able to look inside the case and read the information on the motherboard/cards, put the model numbers in google and you should be able to tell what they are. Always download the latest drivers. Don't use your installation CD, or the microsoft drivers for the device that came with windows.
Obviously your first issue was with no video drivers, and now you're having an issue with no network/motherboard drivers. After installing motherboard, network, video, and audio drivers, you will then need drivers for whatever other devices or peripherals you have. You'll also want to install the latest service pack for xp (sp3) and any other critical windows updates after that.