I love vacuum tablets, though I have never tried the Oreck ones. Hoover used to make vacuum tablets. Sears Ultra Care line has vacuum tablets with a scent nearly identical to the old Hoover ones.
I break the tablets up into 3 or 4 pieces.
Lately I am using air freshener sheets. I shred them up and put the shreddings into new vacuum bags. Still debating how great they work and how long the scent lasts. I think a lot depends on what scent of fabric softener sheets you get.
All of these methods are just covers or another scent to mask the unpleasantness of the stale, old, germ infested dirt that is in the vacuum bags!