For non-video card drivers... I usually just go to the manufacturer's website. If it's a random NIC or something I found in a pile, I look up its pci vendor code at pcidatabase.com .. you can find the vendor number in the device manager, properties, details tab. It'll say something like PCI\VEN_1317&DEV_0985, which works out to be a Linksys NC100 Fast Ethernet Adapter. Download drivers from Linksys' website, and boom.
For video drivers, I download the new ones to desktop, uninstall the old ones, reboot, use driversweeper to get 100% rid of leftover files, reboot again, install new drivers, reboot one more time. Time and experience have taught me that, yes, all the stupid rebooting IS needed. Grumble grumble.