Hughes and Samsung made a series 2 with 120 gig HD, I haven't seen a distributer selling these recently but you can get a 80 gig and upgrade the HD in it. www.weaknees.com I believe sells upgrades and kits.
Samsung SIR-S4120R is one of them. I've got one of these that I purchased off eBay for $35. It had a bad hard drive in it. I got a 80gb drive to replace the 120gb one, just haven't had time to load the Tivo software onto the drive yet.
Its the SIR-s4120R I am positive it is 120 gig. It says it on the box. The funny thing is I run out of room all the time. I can't imagine anything less then 120 gig. Where do you get that mod from. I would like caller ID myself and usb ports