iF YOU ONLY HAD ONE HARD DRIVE, IT WAS A PRIMARY HARD DRIVE, AND CONTAINED THE OPERATING SYSTEM. the operating system from one computer (motherboard) will usually not be compatible with another one.
thus, you would have to format and install an new operating system on it.
If the new computer already has a hard drive on it and operating system, you can install the old drive as a slave to the first hard drive. The problem is if the old drive is very much older than the new machine, it is probably going to be a slower drive, and will slow down the primary drive. in that the primary drive will only operate as fast as the slowest drive on the cable.
my suggestion, would be to get a matching drive and install it. and as long as you are at it you might as well buy the biggest drive you can get you will need it.
