My first source of drift wood was to purchase a piece of wood from the lfs out of its reptile room.
First of all, it took boiling it SEVERAL TIMES (like over a dozen times, each time being at least 1 hour) to get MOST of the wood to sink. The thickest section of the wood would still try to float so I finally attatched it to so slate to ensure it would hold under water.
I placed the wood in my fish tank over a month ago. Even though I tried to boil the heck out of it, it continues to leach tannins. It doesn't make the water black, but with PWC, I can easily see the color of the water when it gets emptied into a white bucket.
Other wise, the single biggest issue I've been having with it is alge eaters. I started with a group of alge eating shrimp. They were basically eating the drift wood. But what was so bad about that was that the tiny little wood pieces (at first I though it was little shrimp poop) litter the bottom of my white sand bottom tank making it look trashy. So I evicted the shrimp and replaced them with a nerite snail. The snail is just as bad as the shrimp.
So my advice if you are going to use this wood in your tank, either use a dark color substraite, or don't expect to have alge eaters.
On the other hand, for my other tank I recently aquired a piece of the mopani wood. The stuff is really cheap at the lfs that carry it. As an example, I know 'Pets America' carry the stuff (7-8" can be like $10, 12" around $12-14, and 18" around $20). By constrast, the drift wood I see offered at 'Pet Supplys Plus' is very expensive... but then again it's not the mopani, and it looks like it's been well treated.
The mopani just needs a single boil to ensure nothing is still alive on it, it sinks pretty much without boiling/treating it (part of the reason I think it's so cheap) and it does NOT quickly leach tanins into the tank.
So unless you don't mind the short commings I've listed for the type of wood you've got, I'd suggest throwing it away and get some of the cheaper wood.