It all depends on the drivers you update.
Updating drivers is a smart thing to do. Often a lot of issues are resolved that you may or may not have been experiencing. This has even happened to a friend who got Age of Conan. After he updated his drivers for his graphics, the game ran twice as fast and much more smoothly. Updating drivers such as graphics, sound and any PCI, AGP or PCI-E device the needs said drivers.
Some drivers are often left alone unless you are experiencing issues, as Dennis has said. Such as your motherboard (chipset) which handles SMBus, USB, AHCI/RAID/SCSI, PCI-E, PCI, AGP, onboard audio, onboard video, etc etc.