If you are running an older OS (Win98?) it won't recognise NTFS formatting.
If you are running Win2k or WinXP it might not recognize the drive immediatly.
On my Win2K-SP4 system I'l literally forgotten that I was "Testing"
a recently aquired used HDD and had it suddenly pop a "New Hardware detected" message several HOURS after the last bootup.
Make sure that you have the power OFF while connecting any drives.
Not only to protect the drive but to prevent dammage to or destruction of the drive controller on your mother board.
The OS that might be (probably is) on any "strange" drives
would be very unlikely to boot on your system unless your system
is identical to the system the drive was removed from.
Registry files are all different.
XP (any version) probably won't work even if everything IS absolutely identical because XP even looks at the unique serial number of the mother board.