Here are some various notes on putting the hardware together and setting it all up.
The motherboard's power switch connector is at the back of the case; I have no idea why (maybe that's the standard for micro atx?), but it causes difficulty because the case's cables don't reach. I had to drill a hole in the front of the case so that the power switch would reach (it has to be plugged in otherwise it can't be turned on).
The motherboard's BIOS screen doesn't work over DVI (it does work over VGA and, I believe, HDMI). It caused me some difficulty since I was connecting the tv with DVI, but it didn't cause too much trouble.
The included Antec Fusion remote worked, but its button layout is pretty bad. It's workable, and the mouse emulation is cool (and occasionally useful), but it's not a remote that you can hand to your wife or houseguest and expect them to be able to do anything.
The TiVo Slide remote worked, but it took some work to get it into a decent state. Windows recognizes it as a bluetooth keyboard, and many of the keys work out-of-the-box. The arrow keys on the slide-out part work great, but the arrow keys on the face of the remote do not. After searching around for a while, I found that the best/only options are Intelliremote and Event Ghost. Both of them will help you map any of the keys, but they don't register the key-up and key-down as separate events, so you won't be able to hold down the key and have it auto-repeat. The Slide can be easily programmed to control the tv power, input, and volume keys, but the volume will be sent both over IR and bluetooth, so your tv will change volume and so will your computer- Windows will intercept the volume up/down keys and there's nothing you can do to stop it. I was having a problem where after a while, the TiVo button presses would cause high cpu usage and make the video stutter; I found a solution in installing the Broadcom bluetooth drivers.
I like the TiVo fast-forward/rewind speeds (3x 20x 60x); you can tweak Media Center's speeds via the registry- instructions here. I also changed the skip forward amount to 30 seconds and the skip backward amount to 7 seconds to match TiVo; the instructions are similar to the ff/rew tweak.
On a similar note, Windows Media Center has a super useful feature- you can type in a time and hit play to go straight to that time. There's more; it's detailed here. It works weird when the show is still being recorded- you have to type in the actual time you want it to go to (instead of hitting 10 to go 10 minutes into the show, you need to type in 640 to go to 6:40, to go to 10 minutes into the show).
Media Center Studio is an awesome tool to customize your start screen, but its development seems to be abandoned. I think there's other tools out there that will work, but I didn't use them. One important fix for MC Studio is here- it seems that a Windows Update broke the customization, but there's a fix.
I found this guide on enabling concurrent sessions to be fantastic- you can use remote desktop to log into the same user that's logged in, so you can install/tweak things without interrupting the person watching tv.
If you want to use the PrintScreen key to take screenshots of the video, you'll to enable it via the registry.
If you want MC to use two different tuners to record two back-to-back shows on the same channel (e.g. NBC Thursday night shows that end the first within seconds of starting the second), it can do that, but you have to set it to record 10 minutes after the end of the show (5 won't work) on every show that it happens for. You can read about it here.
I had jerky video (noticeable on slow pans); I'm not sure if the fix (to disable refresh rate change via registry) here actually helped, but some combination of running the tv configuration thing and registry hacking eventually made the problem go away.
The Antec Fusion case use iMon/SoundGraph drivers; the ones included in the case work fine. One thing that I wanted was to disable the volume knob, so that the kids couldn't change the volume. The earlier drivers let you configure the volume knob to control an empty output (effectively disabling the knob), but later drivers "fixed" this problem and thus the volume knob always works (d'oh!). On the subject of the iMon drivers, if you use the tweak to enable concurrent logins, the second login will run the iMon software, which will screw up the LCD display, even after you exit the second instance.
On the subject of kids, you can tell windows that the action for hitting the power button at the front of the screen should do nothing. I recommend this.
The Antec Fusion case is big- it's full-height. I must have realized this when I bought it, but it's quite a contrast to the TiVo that it was replacing.