Newbie HDTV Questions

[GRGT1994]

I'm interested in building a LinuxMCE system, but have a few questions to start.  I know a bunch of this is probably already answered in other posts, but since these are probably common beginner questions - it might not hurt to consolidate some thoughts in a thread too.

What are the options for recording HDTV?  Are there tuners available that will pull the HD channels from a cable service (not just the local networks that get bundled in, but the Discovery and other like channels)?

Is there a practical limit to the number of tuners you can install (2, 4, 6?)?

I'm interested in automating conversion for portable media players (like the PSP or Creative Zen).  I'd probably be converting standard (480i) content for portable use, but possibly also HD if possible.  Are either fairly easy to implement for a newb?

Thanks for the help.