Does Software Activation helps stop piracy, not really. The latest and perhaps the biggest example is Windows Vista.
Windows XP and Office XP use Product Activation to reduce piracy.
On installation (of non corporate editions) they create a snapshot of the PC is hardware which covers:
Boot disk volume serial number
Network adaptor MAC address
CD-ROM drive ID data
Graphics card ID data
IDE adaptor ID data
SCSI adaptor ID data
Hard disk ID data
Processor Model and serial number
Amount of RAM
Dockable (laptop) or not (desktop)