WoW latest Patch - multiple PC question

[Zathan666]

I stopped playing WoW in the Molten Core 40-man era.

Anyways, I just bought burning crusade + WOTLK. I had to download a ~5GB patch after installing the game. After installing it, I have to download another ~6GB patch. I'm on limited bandwidth and I just can't afford it. Each additional GBs cost way too much on my current plan.

How could I update my WoW 4.0.0.12911 to the latest patch without downloading it? Can I copy some file/folders from my friend's PC "updated" WoW installation. If yes, which files or folders?