I run a Mac (not sure if this works on Windows). If I go into the minecraft folder and under the "mods" folder, all I have to do is drag and drop the .zip files into there and it loads and runs the mods fine (as far as I can tell). I've only tried it with buildcraft and whitegold, and not at the same time, but I'm wondering why it is necessary to open up and manually place the files in the minecraft.jar when I can just do it this way?
Faster Way to Install Mods?