I have two TiVos going free; one has a TiVoNet card and had drives upgraded to ~160G (can't remember the exact figure) - unfortunately it no longer powers up. The other is entirely unmodified and rarely used (still has protective tape on the front of the box). I checked that it still powers up, which it does, although the hard drive (or drives, not sure if it has 1 or 2) sound a bit whiney, so probably need replacing soon.
Also all the bits - IR blasters, remotes (one works, one probably doesn't), and original boxes. I no longer really have the time to keep them going, so I'm giving them away, otherwise they get thrown out. I've no idea what's wrong with the non-working one; it could be just the PSU, or something more fatal.
I'm in Cambridge; let me know if you're interested.
Thanks,
Will