Patch mirrors - WoWWiki - Your guide to the World of Warcraft
EDIT:
Installation tips Edit
The quickest way to get a fully-patched WoW from a clean install is to find a Wrath DVD and run it. The Wrath DVD alone will install all previous patches and get to 3.0.2. From there, install the <anything>-to-3.3.0 patch. There's no need to run the Classic and BC installs before the Wrath install.
If you have multiple locales installed (for addon development or otherwise), you have to move or remove the extra locale folders from Data or the updater will die with a message that looks similar to this:
Cannot find data for {locale} locale.
If you have a US account and install any locale other than enUS, you must edit the realmlist.wtf file or you will not be able to log into the game. The same goes for using the enUS version with an EU account (not that you would since enGB works just fine).
US account with any locale other than enUS
set realmlist us.logon.worldofwarcraft.com
set patchlist eu.version.worldofwarcraft.com
EU account with enUS locale
set realmlist eu.logon.worldofwarcraft.com
set patchlist us.version.worldofwarcraft.com
Manual/split patches Edit
Unzip contents to your WoW directory and double click the file Blizzard Updater.exe or BNUpdate.exe to start patching.
Blizzard Updater.exe and BNUpdate.exe check for ".\Data\{locale}" (the current directory), "..\Data\{locale}" (the parent directory), "..\..\Data\{locale}" (the parent of the parent directory), until it hits the root of the directory structure (where it informs you that WoW must be installed before it can be patched), for Game data (not tested on any paths deeper than "C:\Program Files\World of Warcraft\Patches\{patch folder}\{patch data}"); therefore, you must put the patch files directly in the WoW installation folder or in a subdirectory of said folder.
For example, the following all work for "WoW-2.2.3-to-2.3.0-enUS-patch.zip":
unzip the files to "C:\Program Files\World of Warcraft\WoW-2.2.3-to-2.3.0-enUS-patch" and double-click "C:\Program Files\World of Warcraft\WoW-2.2.3-to-2.3.0-enUS-patch\BNUpdate.exe"
unzip the files to "C:\Program Files\World of Warcraft\Patches" and double-click "C:\Program Files\World of Warcraft\Patches\BNUpdate.exe"
unzip the files to "C:\Program Files\World of Warcraft" and double-click "C:\Program Files\World of Warcraft\BNUpdate.exe"
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