We’ve got a new TiVo Upgrade kit out there: 40 GB. The 40 GB kits are “replace” type kits (more info on that here) for the oldest standalone models out there. These are the Philips HDR series and the Sony SVR-2000. A 40 GB drive in either of those units gives you about 40 hours at Basic Quality and about 12 hours at Best Quality.
The new kits are $99 and we’re using good old Maxtor QuickView drives in them!