Hi there Wayfall,
You can just clone the old drive onto a new one. You will just need a SATA and power cables in order to attach the new HDD to your system and perform the cloning process.
You can use Acronis True Image WD edition:
http://products.wdc.com/support/kb.ashx?id=n8UmrW
After that, I guess you can test your old HDD with WD's DLG tool(both short and extended tests) and see if there is something wrong with it:
http://products.wdc.com/support/kb.ashx?id=tr3i4n
If the drive is in a good condition, you can reformat it and use it for a back up/secondary storage drive.
Let me know in case you have some more questions,
D_Know_WD