you wont be able to level from 61-70, you have to have BC to get through those levels and for the Draenei and Blood Elf races. plus i think BC is required for Wrath

It won't work... I tried it. You must buy BC first because otherwise when you enter the key in it says "ERROR: CODE IS FUNKY" or some variation. I tried this 5 times so I'm positive my code was right. Bought BC and it upgraded perfectly.

Wotlk requires BC.

Error: code is funky? Whoa, slow down with your technical mumbo-jumbo, poindexter.

If you have registered WoW on battle.net (which everyone currently playing is required to do) you can install WoW right from there, without any discs. You must have previously installed Vanilla and BC and Wrath in order for this to work.

I know this because I wanted WoW installed on 2 computers and I didn't feel like installing all the discs so I tried it from battle.net.

This works for any game that you registered on Battle.net. You can even play Warcraft and Diablo without the play discs if you do this.

You just need about an hour and a decent high-speed connection that won't fail you...

To fix ERROR: CODE IS FUNKY, we need to remove the tiny unicorn jumping around inside your computer, poking holes in your hard drive. That'll be $1000...

You do not need to re-install WoW. It works with zero errors if you copy and paste the entire directory onto the new computer. Just create a link to Launcher.exe and you are all set. Only it won't be listed as an installed program, to uninstall it, just delete the DIrectory.