Why do you have a LaunchAndRename command when you're not actually going to utilize the entire command?

Just change it to
Code:
<Hotkey Alt Ctrl T>
<SendPC Local>
<Run "C:\Program Files (x86)\World of Warcraft\_retail_\Wow.exe">
<RenameWin "World of Warcraft" HiddenDialogBox1>
<RenameWin "World of Warcraft" WoW1>
<TargetWin WoW1>
<SendWin WoW1>
<text [YourUsernameHere]>
<Key Tab>
<Wait 100>
<SendWin WoW1>
    <Text [YourPassword]>
<Key Enter>
<TargetWin WoW1>
<SetWinSize 1920 1050>
<SetWinPos 320 0>
Also, what if one of your three clients crashes? With your script, you'd have to restart all three clients instead of the the actual one that crashed. This script also logins automatically for you so you don't have to remember username and password for multiple accounts.

I'd change the hotkey to
Code:
<Hotkey ScrollLockOn Alt Numpad1>
For the first client, and add the code below it. Do the same for the other two clients.
Code:
<Hotkey ScrollLockOn Alt Numpad2>
So essentially, pressing Alt + Numpad 1 to 3 (with ScrollLock On) starts each individual client for you. Logins automatically, resizes it and moves the window to its correct position. You can also start everything holding Alt and pressing Numpad1, Numpad2 and Numpad3 and it will start everything for you.

Having the entire start order in one sequence is a bad thing