I know this is an older thread but I am new here and have found a lot of good advice from my questions so I wanted to help you out in return.
Tivo also is a good option to use as a DVR. Tivo works with OTA or Cable. It works very similar to most cable DVRs, record two shows at once. I have the Tivo HD DVR, it holds 20 hours of HD recording. You can buy external storage to store more. As long as you have an antenna that gets signals you hook the coax up to the back of it and scan for channels and your set. I think newer Tivos can record more shows than 2 at once and have bigger built in hard drives and other features, you can check out the products at
www.tivo.com
It requires internet to pick up the guide, and you can get a wireless connection to it as well.
Other features that Tivo has is you can stream Netflix through it, Youtube, and Amazon. I believe the newer Tivo Premiere also has Hulu plus.
Tivo can be costly but they run specials on the equipment. You do have to pay for service, which can be monthly, yearly, or lifetime (lifetime is expensive, I've seen it from $299.99 on special to $499.99 currently). I first bought my Tivo in 2008 and have since gotten my money back. In having cable for 3 years, instead of paying month $11.00 for the box, $8.50 for DVR service and .70 cents for a remote, totaling $20.20 a month, $242.40 a year, three years of $727.20. The cable company charged me $2.00 a month for a cable card.
Tivo works with Antenna or Cable only (not Uverse) (there is one that is designed to worked exclusively with Direct TV as well). If all you want is analog cable you just connect the cable coax to the back of the Tivo (it has another connection for Antenna, can have both connected at once). If you want digital cable, the cable company will provide you with a cable card, about the size of a credit card that is inserted into the Tivo, and a Tuning Adaptor to pick up the Switched Digital Video (SDV) channels. The only thing that the Tuning adaptor cannot get is on demand channels.
Also if you have more than one tivo you can transfer programs from one to another (as long as it isn't currently recording). Some cable companies have copy control where you can only transfer broadcast channel programs, not cable channels. I know Time Warner does this, not sure about others.
So that sums it up, a lot of info to throw out there.