Here's a help file with some info on how our HDDs work, deleting titles, etc.:

http://www.avsforum.com/avs-vb/showpost.php?p=12798560&postcount=243

There are also two "ahrsher" methods using SKIP codes that delete everything from the HDD. SKIP 079 + OK does a HDD Format, and SKIP 013 does a HDD Factory Check, which also deletes everything from the HDD, as described here (use these only if you want everything gone from the HDD):

http://www.avsforum.com/avs-vb/showthread.php?t=940657

Other help files on setup and operation are here:

http://www.avsforum.com/avs-vb/showthread.php?t=940657

The hard drive is running all the time.
that is why you can pause live tv.
It has a virtual memory.
at any time you watch tv,you can pause,rewind,ff and record.
page 46 of owners manual
explains special recording

Yes, HDMI output with 480p, 720p, 1080i and 1080p output selection via remote.

Yes, but only if channels are received in proper sequence. Mine could record all except 2.1 and 2.2, which appeared after 2.9.

You can record up to 49 programs to DVD. However, the maximum total time that can be recorded varies from 60 to 360 minutes, depending on the desired quality.

The HDD can hold 600 programs, and from 30 to 180 hours, depending on the desired quality.

You can transfer programs recorded on the HDD to DVD.

Over 120 - I stopped it as I knew I didn't have any more channels available on my cable system. I looked in the manual, but can't find the maximum number of channels available.

Check out this link:
http://www.avsforum.com/avs-vb/showthread.php?t=940657

You can record the following hours, depending on rec mode setting:
1-hr-HQ = 30
2-hr-SP = 60
2.5-hr-SPP = 75
3-hr-LP = 90
4-hr-EP = 120
6-hr-SLP = 180

Those are hours based on the manual, but it has the same HDD as the 3575 and 3576, which shows a few more hours at each rec mode, so numbers are approx.

You can also upgrade the internal 160GB HDD to 500GB in a simple DIY process described here:

http://www.avsforum.com/avs-vb/showpost.php?p=12355769&postcount=39#HDDrep

See esp. the "Pioneers" section that describes upgrades by "normal" users and gearheads alike, along with the increased hours of recording a 500GB can hold (basically over 3X the OEM HDD).

No monthly fee if you use OTA antenna, normal cable or sat fee if you use those service providers. No box fees, facility fees, fees-on fees, fee-fee-on fees, etc.

You can record to the HDD anything that your TV can display w/o cable/sat boxes, i.e., channels that aren;t scrambled by the cableco or encrypted by the sat provider.

You can also copy VHS home movies, Many commercial VHS movies (I did 9 of 14 1st run movies on tape), pics, music, and anything that can be sent to this unit via a line connection.

Here's a complete list of help files for more detailed info:

http://www.avsforum.com/avs-vb/showthread.php?t=940657

I don't think you need a splitter. Just connect to a different output on the Comcast box. Don't need HD output just Coaxial since it's not a high def recorder. Thats how I did it. Use a different input source for each on the TV for the HD TV, DVD player, and DVD Recorder/Player. I use Coaxial input from Comcast box to the Magnavox recorder. Set input channel to 4

Turn off the auto clock setting and then set your clock.