Well, here's one way to fill that new 1TB drive you just attached to your TiVo: purchase and download a movie from Blockbuster onto it. More than 100 movies are being offered at launch, with new titles at $5.95 and older fare for $3.95 a pop.
The presence of Blockbuster (which has been running trial giveaways of selected movies on Tivo since last year) should have alerted you to the fact that this is a rental service, not an ownership deal. You can store movies for up to 30 days, but have to finish watching them within 48 hours of starting. Typical movie sizes are said to be 1-2GB. That could be a expensive way to power through your cap, unless you're an Internode subscriber, in which case downloads aren't charged. You can schedule downloads for 2am to take advantage of any off-peak hours with your ISP.