Software

I use DriverMax - works great for me!!http://www.drivermax.com/index.htm

is just to get the drivers from the OEM system builder's support site for your exact model computer. Best method.

Anything still missing:

If you are having issues identifying devices
http://www.zhangduo.com/udi.html
Unknown Device Identifier

Driver and other system information
http://www.gtopala.com/
SIW

Back up and update drivers
http://www.drivermax.com/
(There are others like this, but this one works well, in my experience.)

The problem with most driver update software is that they rely on the information in the registry for the existing drivers and just let you know when newer versions of the drivers are available.

Most will not find drivers for unknown hardware. Nor, do the algorithms and databases that driver update programs use know when the newer version of a driver should not be used with older hardware.

seanferd gave you links to ways to identify unknown hardware. It usually is not difficult to identify the hardware that is missing a driver with just a little investigation.

Keep in mind, if the problem with a device is a will not start error, just updating the driver may not correct the problem.

Just as I have become very cautious when Microsoft Update suggests I need to update a driver, I don't trust automated driver update software. I would much rather research and get any needed updated drivers from the system or hardware vendor.

Chas