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Why would you need to? You can download the game at anytime from Blizzard.

If you really want to, use Disk Utility and make a .dmg of the DVD.
 
untrue, at the mo the wrath of the lich king client needs a small bit of date from the wrath dvd, god knows why and currently you cannot download the client from their website.

saying that this is only needed for people with wrath subscriptions
 
Early this morning I started a download from Blizzard of Wrath of the Lich King. When it was completed, it reinstalled patches 3.0.2 and 3.0.3. A few hours later, I went to pickup my copy of WotLK at Best Buy. I opened the box, found the authentication key sticker and used my iPhone to upgrade my account. When I got home, I logged in and started my Death Knight.

You don't need the DVD. If you feel like you do, you can have mine. It is now resting in the dumpster behind Best Buy.
 
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