As said, not TiVo allows you to connect a USB HDD to it for any reason.
The Series 3 does not support in-home transfers at this time, which is the only way to digitally get recordings from a TiVo DVR that would otherwise support such transfers.
You can add an eSATA drive to expand recording capacity, buy you can't choose to put particular recordings onto which drives, copy from the internal to external, or connect the drive to a PC to access recordings.
If you want to use a USB drive to store recordigns, you can connect one to your computer and TiVoToGo to it, if transfers were to be enabled on the S3, and copying permssions allow it.
Series 2 234 Hr Lifetime.
Window XP and Ubuntu Linux on my PCs.
Watching more and more in HD direct now.