Just use it, now. Don't worry about the software, just leave it alone. Don't reformat it, just use it.
And I wouldn't do what you're planning to do. An external drive is more likely to fail than an internal drive because it's more likely to be bumped, dropped, knocked over, etc. If this drive fails and all your data is in that one place, you're in trouble. It will cost a LOT to get it back. Make sure your data is on two different storage media. Internal drive, a 2nd external drive, CD, DVD, whatever.
