Switching drive from hitach to samsung need more than just inserting the key. Check out http://forums.xbox-scene.com/index.php?showtopic=559861
For the key portion, did u install xtreme firmware mod. on the hitachi drive previously? If u do, u will have this key.bin file. Just inject it to your samsung drive.
First dump out the samsung drive firmware. Inject the key, this will be your original samsung firmware. Then do the xtreme firmware mod if you want to. You should get the E66 error and you have to fix it based on the link that I had provided above. If you don't get the error, then you don't have to do anything mentioned by the link above, just inject the key alone.
To inject in the correct place, look at samsung original firmware dump. Go to 0x40EC, you should see the key that comes with the drive. Copy and paste the 16bytes hex value of key.bin onto it. However, before doing this check 0x4116. Is it "FF" or the start of 16 bytes of different hex value? Cos if it is all "FF", then the key is at 0x40EC. Else the key could be at 0x4116 and you have to copy and paste accordingly.
Of course, before you do anything, make a backup copy of everything first.