New and don't know where to start

[Apollo22]

So, first off, i'm new and not much of a gamer. A friend suggested talking to a few people on here that might be able to help. My girlfriend was cleaning out a bunch of boxes the other day that her dad left behind after her mom passed away and found a few games. She asked her dad about them and he didn't really care to much. Pretty much all the games that were in the box he received as gifts. Never played any of them. The only one he considered playing was World Of WarCraft. And the only reason he considered it was because of everyone going crazy about it at the time. He opened the box and never made it any further than that. All the items in the box are still in their original packaging. The only packaging that was opened was the plastic the box was sealed in. Every one I have talked to so far seems to think I have a jem here. I have no idea. I was hoping some of the members here could help tell me a little about what I have.
From what I under stand it is the World of Warcraft the burning crusades collectors edition. They tell me its vanilla. What ever that means. And that I should hold on to it. I guess what i am asking is how can i tell if its valuable and why is it so valuable? I was considering giving it to my nephew who is a huge gamer and wants to go into video game design and programming. Figured he might like it but i don't even know what kind of games hes into.
Any insight would be greatly appreciated.