I've recently moved from MythTV to WMC7 -- only because TimeWarner decided to 'copyflag' nearly everything my family watches. I wish I could go back to Myth. I feel like a member of our family has died.
I run WMC on a box in the home office with an HP x280n in the kitchen and a Linksys DMA2100 in the bedroom. Both extenders were purchased used off Ebay for $90 each.
I have an HDHomeRun Prime HDHR3-CC (CableCard) and 2 original HDHR dual tuners (clear QAM).
The HDHomeRun Prime comes in a 3 tuner model and a 6 tuner model. The 3 tuner takes 1 CableCard, the 6 tuner takes 2. The CableCard you need is known as an 'm-card." An m-card can handle 4 tuners.
If your cable provider is using "SDV" (Switched Digital Videl?) you will also need a Tuning Adapter. This is an external device with it's own power wart and connects to the Prime by a (in my case, very short) USB cable.
I prefer the HDHomeRun products because they are Ethernet based. This has 4 advantages over internal or USB tuners:
1) You don't have to open the box. It may not sound like much, but being able to just plug in an Ethernet cable is way better than fiddling about inside the box. Fewer cables attaching to the box makes it easier to man-handle as well.
2) You can access any tuner on any endpoint (computer or extender). We never watch live TV so this doesn't matter much to us.
3) You can see the 'lights' on the boxes which can help with diagnosing problems.
4) You can locate the tuners where it makes the most sense -- keeping a lot of mess out of the way. See what I mean here:
I put all the HDHRs in the attic where the cable TV enters. A Gbit switch also in the attic connects the HDHRs, the extenders in the bedrooms, and the home office where more switches and computers live.
So far, I'm not impressed with WMC. This may be due to my ignorance of W7 and WMC. I'm a Linux weenie.
It seems slow to respond to the remote. This may be because W7 is running on an Atom 525 with 4GB of RAM.
It doesn't automagically strip out the commercials. Myth would just fade in the 'progress bar,' show 'Skipping 3:46' and fade away.
It can't MultiRec. Each tuner can tune 1 channel. Each channel can carry a bunch of program streams. For example, TimeWarner puts XETV-HD (CW), KSWB (Fox), and KGTV-DT (ABC) on the same channel. Myth could record all 3 and only tie up a single tuner.
You can only record to storage directly attached (SATA, USB, etc.) to the recording computer. The registry hacks I tried to record to my network file server seemed to go away randomly.
You can't do anything with the recorded content because of DRM. 'Your' recordings are tied to the computer that recorded them. If it dies, so do 'your' recordings. With Myth, I could load up a USB stick or burn a DVD and watch where and when I wanted. Supposedly Myth can re-encode for an Ipad or Iphone but I never did this.
It won't play my 700+ HandBrake encoded movies. I suspect this is an AC3 codec issue. Myth would play anything.
I could go on, but this isn't a Myth vs WMC bashfest...