Need help with reclaiming MAC external hard drive space

[EllertMichael]

Hey friends,
I haven't been able to find the answer to my problem anywhere, maybe someone here with some know-how can help me out..
I have a 1 TB Western Digital My Book for Mac external hard drive and I've currently got just under 100 gigs of files on it. However, it says it only has 617.98 GB available.. is there something I can do to reclaim this empty but used space?
I started a very large torrent download (145 gigs of MST3K) which I then changed my mind on (poor seeding) and deleted, however it didn't free up the space that it allotted.
I apologize if this is an obvious fix, but I'm still very much a MAC noob..

[Niode]

Empty your trash.

[Hobie-wan]

Empty your trash.

But it will throw out my floppy! Those are hard to buy these days!