Hello,
I just wanted to thank TiVoMad , Tiger and Kazymyr for making my TiVo upgrade easy. I installed a Western Digital 100GB ($120USD with rebate from Sam's Club) as the B drive in my TiVo and it was a piece of cake.
I followed the directions at http://www.newreleasesvideo.com/hinsdale-how-to/

Ragwing
Phillips HDR212, 141 hours 49 minutes