Not sure what satellite system you have, but DISH Network has an HD package you can subscribe to with about 20 or so HD only channels, including Showtime HD, HBO HD, TNT HD, and ESPN HD just to name a few.
We just signed up for DISH network. It gets installed on Thursday!! WooHoo.
VOOM is the best at HD content. I believe DirecTV is getting there with TIVO but there are content issues and recording via DVI or firewire between studios releasing their content and satellite providers.
The market is getting quite complex with HD.