Getting back into combined HTPC / DVR

I’m preparing to get back into having an HTPC that is both a DVR for Cable as well as an interface to internet streams and my home video library.

A little backstory…. About 10 years ago I started using MythTV, but not much because I was poor.  Then I had Satellite about 7 years ago and we had a TiVo unit which had the highest WAF of all my units to date.  The TiVo kept having hard drive failures requiring me to hack a re-install.  After the 3rd failure I trashed it because newer units were out and DirecTV at the time was dropping TiVo.  We then went back to Cable and MythTV and it worked great.  I had a machine in the basement with 3 or 4 tuners, both analog and ClearQAM.  We were able to get most of the channels we wanted and with the storage on the backend, that left just a lightweight machine next to the TV, though my wife still hated having a computer in the family room.  We used this for several years, moving houses and setting up on another Cable company.  The hardest part was buying something powerful enough to deinterlace, etc properly without skipping.  About 2 years ago, we had to change again because the cable company was dropping all analog signals and I didn’t want to fool with getting 3 “mini” boxes and setting up IR blasters.  We probably get several ClearQAM channels still.  After the switch, I basically shut down my MythTV boxes (I was trying to virtualize the server at that point), and I tried Boxee for a few months and I ended up on XBMC for the last 2 years or so.  It works great to browse some internet TV streams and manages our home library great.

I’m ready for change.  I’m not limiting myself to Linux systems as I have in the past, but I want something DIY. Buying commercial applications is not out of the question,only super expensive hardware.  My goal would be to have a DVR system that would record in one place and allow me to playback from multiple TVs.  I would also love plugins or naive support for things like Hulu Desktop, channel streams such as USA, Fox, ABC, CBS, Comedy Central, etc as well as a good media manager.  I was planning on buying an HD HomeRun Prime to get access to all the cable channels, although my Cable company as of last summer told me they wouldn’t give customers M-stream cards (but their own equipment uses them).

So any thoughts?  Is this possible?  My current system is an Atom dual core 1.6Ghz machine and has been handling video fine.  It is driving a 720p LCD, but I want to go back to 1080p and we’re buying a new TV for that.  My current machine is working its hardest when it is streaming videos from a CIFS share where I have encoded videos.  So it is decoding Xvid etc, and no hiccups.  What is the current recommendations on low-end, low-power HTPC front ends?

TIA