Another recommendation to use Weaknees or another company that provides pre-formatted TiVo drives. More expensive than buying your own and formatting it yourself, but certainly a lot easier and if the OP has never prepared his/her own hard drives before, certainly recommended over the DIY solution.
In addition to Weaknees, there is also Digital Recorder, DVR Upgrade, and others, just type "TiVo upgrade" into your favorite search engine. Occasionally I even see ads for hard drive upgrades on this site as well.
Oh and buy the biggest hard drive your budget will allow. GB's are getting increasingly cheaper by the day, and you'll find that larger hard drives are often not much more expensive (and occasionally a bit cheaper) than smaller ones.
In addition to Weaknees, there is also Digital Recorder, DVR Upgrade, and others, just type "TiVo upgrade" into your favorite search engine. Occasionally I even see ads for hard drive upgrades on this site as well.
Oh and buy the biggest hard drive your budget will allow. GB's are getting increasingly cheaper by the day, and you'll find that larger hard drives are often not much more expensive (and occasionally a bit cheaper) than smaller ones.