Alright, so I downloaded the World of Minecraft client and the minecraft.jar file (from several places, just to check).
I've tried everything to get the minecraft.jar file to that darn lib folder, I've tried extracting it to the folder, simply dragging and dropping, I've tried renaming the file. I've tried everything short of killing a small child, and every thing I've tried has led to two places;
1. I get an "Access denied" message with errors "Cannot rename/create file"
2. The file doesn't show up at all anyway.

So what am I doing wrong?