If you get a -3.5dB, 5-1000MHz, 2-way splitter ($10-$12 max), you can send one leg to the cableco box with the other leg going to analog devices like a VCR, the TV (PiP/PoP), or a Tivo. I send the second leg to a distro box supporting all those and a second room TV. The specs for the splitter are important since the HD cableco boxes are quite particular about getting the correct signal levels, not too high or too low. My Moto 5100 HD box also has a coax out that can send signal to the distro box so those analog devices can also see the digital channels.
YMMV
PS - My cableco advertises the box but as recently as Saturday night told me they are not yet available; still being tested.
