You can get all the patches here at
Fileplanet
To find your current version of wow goto the games logon screen and it is in the lower left corner. Get the patches after the one you already are at.
Place the files in the root world of warcraft directory (/world of warcraft/).
If it still needs to download stuff try placing the files in the /patches directory. All patch files can be deleted after updates.
Also if you have either a 2nd HDD or a DVD burner (Dual layer recommended) you can back-up your whole WoW directory and then move it back. I have a back up from a few patches ago (i backup my addon and wtf folder before a reinstall of my OS) and I install WoW and BC then copy my backups over to the new install and get the few patches needed and off I go.
Patching from a first run disc sucks as it is so out of date
