Depending on the source of the drive...you probably ought to delete everything on it, IMO.
If the hard drive came from a different system...the drivers/settings are probably not compatible with your hardware.
The hard drive may be infected, no one likes to consider it...but it happens.
If it's a drive from an OEM (Lenovo/HP, etc.) system...and you don't have a valid license to use said drive in a different system...you will have Product Activation issues, even if you don't have drivers/settings issues.
Changing a Motherboard or Moving Hard Drive - http://www.michaelstevenstech.com/moving_xp.html