I've got a series 1 UK TiVo and I can extract stuff off it easily. You just need to install the TurboNet card into the Tivo and then the tyStudio software on your PC and Tivo. It's all point and click after that. You select the show you want from your PC and it'll download it, reencode if you require it and that's it.

I've got a single 120GB drive in there at the moment and I'm considering uploading a new kernel with the LBA48 (I believe it's actually using Mark Lord's patch to get LBA48 on 2.2.x kernels actually) so I can get a 250GB or 300GB drive. I've expanded the RAM on the Tivo as well but I've not noticed much difference...