My box is the PVR-3080 model which means it's the standard definition. It's extremely easy to upgrade your Motorola PVR (DVR) with a bigger harddrive. (Definitely a 1-banana project on the Shade Tree Howler Monkey scale
The stock harddrive is an 80 gig SATA and it just wasn't big enough for my needs. Ok, actually it was fine... I just like taking things apart and tweaking them! The specs claim you can record up to 60 hours of Standard Definition programming. However, I maxed the harddrive and was only able to hit about 42 hours of record time. The shows were a pretty even mix of 30min, 60min and 120min recordings.