Build a Home Theater PC with Win Vista or 7 Home Premium and above and dump DVR boxes, watch and record 1080i premium (copy once / encrypted) cable programing and share over wireless or wired network to other TV's via Media Center Extenders. The ultimate multi-room viewing solution with excellent DVR software of Windows Media Center.
The ATI Digital Cable Tuner (recently discontinued) has 1 HD tuner that allows capture of premium / encrypted content (you need Vista or Win 7 with cable card and tuning adapter. Check ebay. You can add multiple cards to get more tuning capacity.
Ceton is about to release (hopefully, delayed several times) a 4 Tuner card that works with 1 cable card and 2 SDV tuning adapters that also allows capturing encrypted cable content.
Silicon Dust is expected to release a network attached 3 tuner cable card compatible card before the holidays (in beta now).
All work only with Windows Media Center, which has very powerful and flexible DVR software and internet TV (hulu, netflix, etc)
All allow you to dump the cable boxes. The SDV tuning adapters are somewhat problematic.
Then get Media Center Extenders to share the live and recorded HD content with other TV's around the house. Linksys DMA 2100 and 2200 (discontinued but work well) or noisy , power hungry and fugly XBox's. Work wirelessly (YMMV) and over wired ethernet.
The ultimate multi-room viewing capability. No DVR rentals.
Go to www.greenbutton.com
for additional info.