http://www.wowwiki.com/Patch_mirrors
of course, use the "us" one.
after I installed from the disc I had a 340mb monster to download. not sure which patch that was. there was a smaller one (about 30mb) after that was finished. you should be able to look in yr WoW directory and see which patch you have. once you download, just double-click and it will self-install.
last night was "oh, hey, let's gank ghidrah" night. the results:
me vs. 75 pally and 74 hunter: them
me vs. 73 shammy: ME
me vs. 71 hunter: ME
me vs. 70 death knight: ME
those poor bastards JUST DIDN'T KNOW.