As Microsoft tells it, bad drivers are the bane of a stable computing environment and are one of the biggest contributors to OS crashes.
As a countermeasure, Microsoft has developed the Microsoft Hardware Qualifying Lab. Part of this lab's job is to test hardware devices and drivers for compatibility and stability. If approved, the device bears the "Designed for Windows" logo, and the driver is digitally signed. When installing drivers, those carrying one of these digital signatures appears with a little green check mark and diploma icon, as shown in Figure 6-12.
Figure 6-12. A digitally signed driver.
So what happens if you install a driver that isn't digitally signed? It depends on how the driver signing options have been set. You can access these driver signing options from the Hardware tab of the System Properties dialog box by clicking the Driver Signing button.
The default setting is shown in Figure 6-13.
Figure 6-13. XP warns about non-signed drivers by default.
As you can see, you're able to set three levels of driver protection: Ignore, Warn, or Block. On most systems, leaving the default alone serves you best. After all, you install a driver because you want some new device to work, and so you most likely will at least try to use an unsigned driver before making a return trip to the computer store.
If your XP system is a vital computer in your networkthe file and print server for multiple computers, for exampleyou are probably better off setting the default to Block, and then only overriding it when absolutely necessary.
Ignore is not recommended except in a test-lab environment.