Curtis is right. Weakknees is great, I bought a kit for my HD DirecTivo and took me about 30 min to open, install and close it up. Went from 250 GB to 550 GB. I didn't even have to format a drive. If your friend is willing to work w/ Linux, it's not too hard to buy a cheapo HDD and format it w/ various tools.
Here's some resources and other upgrade options:
Tivo Forums
PTV Upgrade
9th Tee
Some notes on lifetime. It's not a scam, IMHO I think it's a great deal. (Then again, I love tivo.) There's 2 versions though. For standalone Tivo's, you can still get lifetime and it follows the box. So if that box is ever sold, the lifetime subscription goes with it. (Maybe buy the box from him...) For DirecTivo boxes, there used to be a lifetime for the box, but no more. DirecTV makes you pay monthly now. HOWEVER, if you had lifetime before the change, you are grandfathered and the lifetime is now w/ your account. Any Tivo you get for DirecTivo is given lifetime status, you just pay a mirror fee for any additional receiver after the first one. I have 2. In fact, I bought my first DirecTivo on ebay w/ lifetime. Then the rule change happened and it's now applied to my account.
