Rugs, Carpets and Carpeting - Can you use carpet pad under an area rug?

I just removed a bunch of carpet and installed hardwoods. The carpet pad is in great shape, so I was wondering if I could use it under area rugs that are placed on the hardwoods. I like the spongy feeling of the pad under the rug. A non-skid pad could be put down, then the carpet pad, then the rug.

Thoughts?

Not to hijack your thread, but I'm sort of wondering the same thing since I just finished ripping up some old carpet and pad (which was not in any way reusable). I'm about to refinish the existing hardwoods and I too am wondering about what to put under my new area rug. I don't want anything so thick that people are tripping on it as they walk from the wood floor onto the rug. I'll be interested in what any knowledgeable folks reply to your question.

use a thin carpet pad, like 3/8" or 1/4"