Here's a comparison of the before and after pictures for my new Series 2 Tivo.  It was originally a 60 hour unit, but I've upgraded it with dual 120Gig Western Digital disks.

I now have more space available to "Best" quality recordings then I had at "Basic" on the new unit, and more at "Highest" then I did at "Basic" on my previous Tivo upgrade.. a series 1 with a 30Gig and added 60Gig disk.

Capacity Before Upgrade

Capacity After Upgrade

For those that care... I followed the Hinsdale HOWTO for the upgrade process. The new MFStools2.0 kick ass!