When I downloadede quest helper on Vista, I never got the add on folder. Is there a bug in this program for Vista?

no i just did it, you have to make your own folder for the dl, and when you right click on WoW go to open file location and then when you get all the files open interface and you should see them in there. it automatically loads

Everytime I click on something install via curse client because I have curse client, it says error 000000000 something now I cannot put any add-ons on my comp can anyone help me out?

it says fails to connect to previous instance error 0000000 to be a bit more accurate,

You need to make your own AddOns folder under the interface folder in your WOW directory. From there, unzip the addons into that folder.

i saw ur reply on how to do the vist thing and how do i unzip?

You need an unzip program. You can down load one with a free trail. Just google unzip or WinRAR. I highly recommend WinRAR. It still works even when trail is over.