For encrypted Dtv i'm not sure if there's any solution, other then taking the analog out of your set top box, and feed that in your pc through an analog tv card. And use an ir-blaster for changing channels to record (included with the cheap microsoft mce-remote)

For unencrypted i think this one must be good (coming soon, they say) :
http://www.silicondust.com/products/hdhomerun_dvbt

Edit: Found this thing, not sure if it's any good though, usb so i think hd is going to be re-encoded: http://www.anysee.com/eng/product/anyseeE30ComboPlus.php