Connect Motorola DCH6416 to MCE computer

With the Motorola DVR, you can typically use a PC to record content from local channels via Firewire, as it is played. Instructions for that can be found this thread. With rare exception, this only works for the local (including locals in HD) and public interest channels; this generally not work with cable channels on most providers, although there are always exceptions.

If you have a QAM tuner in your PC (or a USB QAM tuner), you could record directly from HD locals using Windows Media Center. This would not do anything for the recordings stored on your existing DVR, however. For more information on that, see the Home Theater Computers forum.

The TivoHD (and discontinued TiVo Series3) is the only standalone DVR that lets you actually login to the DVR and download SD and HD recordings to your computer over your home network, as seen in this screenshot.

I think you are confusing Firewire from an STB with clear QAM tuning with no STB. For clear QAM tuning without a box, yes, you can usually only get the locals for watching and recording because the rest are encrypted. For Firewire recording, I was able to record all subbed channels in the digital preferred pkg (didn't have premiums so don't know about those) on Comcast in the ATL. Many cable systems leave all or almost all of the digital channels unprotected for Firewire because the copy control bits are not implemented.