Digital cable will cost you about $65/mo I think and that includes one HD cable box. My bill runs about $121 with tax but includes $45 for Road Runner service and an extra $14 or so for a second cable box (Explorer 8000). Due to their pricing it is not really a supplemental service to have along with dbs.
TWC currently uses the SA3100HD cable box which has YPrPb component out, digital coax out (no Toslink), and analog audio. It also has S-Video out, and a coax cable out (for vcr), a composite video out, I think there is a USB port on the front and one access card slot (not implemented).
This box has no aspect ratio switch for those who have a 4:3 display. So 4:3 owners may have vertical stretch problems if their display cannot do the squeeze. They will also have four bars around when watching 4:3 upconverts via the component input. The next iteration box (the 4250HD I believe it is called) should have selectable aspect ratios. If one needs RGBHV, Scientific Atlanta makes a HDTV converter but I don't know if local TWC has them for sale.
The box itself rents for about $10/mo including remote and cable guide (as if you had a choice). This is the same price as a standard box. HBO and SHO cost about $15 I think and the HD comes along for the ride (I no longer sub to either). The DVR box costs $5/mo more (but it is not HD either).
Personally I like the interactive menu system on TWC and I miss its features when I am on the Zenith DTV420 box which gives only channel number and program rating (G, PG13, etc). But if viewing 4:3 programming on a HD channel on a 16x9 display one has the black sidebars (yuck).
HD Programming wise you now get:
PBS: WRLK-DT (1 HD, 2SD)
CBS: WLTX (1 HD, 1SD with Weather Radar),
ABC: WOLO (1 HD)
HBO: 2 (east and west coast feeds; if subscribed)
SHO: 2 (east and west coast feeds; if subscribed)
Other stuff: bunches of normal stuff on analog and digital tier plus on the digital tier a number of free VOD channels (all 4:3 SD only) and a few Subscription VOD (also 4:3 SD.... HBO, SHO, Movie Channel).
Hope this helps....
BruceLatest Summary on COLUMBIA SC HDTV can be found here.