Much like the all-in-one, the lightweight front end is intended to sit in your living room, feeding content from the big server in the closet or the study to your home theater. It's fairly low noise and blends in unobtrusively, and probably takes even less power than the all-in-one because it has less hardware inside.
The key differences that result from this are the small, single hard drive and the absence of any tuners; all of the storage takes place on the back end, as does the tuning and encoding. A really light front end could omit the DVD drive and hard drive entirely, but we won't be quite that ambitious. Our take on the lightweight front end doesn't get quite as low power as it could, in large part because we intend for it to support 1080p in all operating systems—this means we include enough CPU power to decode 1080p without assistance from the video card to support current Linux-based HTPC front ends that do not yet support PureVideo/UVD/ClearVideo.
For the Lightweight Front End, take the all-in-one specification and make the following changes:
We put the tuners in the back end, allowing us to slim things down in the front end. The case now holds the motherboard, CPU, memory, power supply... and, depending on your ambition, the hard drive and optical drive. Not much else, which allows it to run very cool and very quietly.
Western Digital WD1600BEVS 160GB 2.5" SATA
With no need for massive storage, the hard drive's primary raison d'être in the lightweight front end is to hold the OS. You could do this over a network boot or even with a few gigabytes of flash memory, but we go the conventional route here with a regular mechanical drive.
2.5" laptop drives tend to run cooler and consume less power than their 3.5" desktop counterparts. The Western Digital Scorpio WD1600BEVS offers excellent performance for a laptop drive, 160GB of space, 8MB of cache, a 5400rpm spindle speed, 12ms seek time, and a three-year warranty.
Cost: $69.40 (4/27/2008) [Comparison shop for this item]
Antec Veris Fusion
We keep the existing recommendation because it's already reasonably low noise and it's fairly well-built. We feel compelled to note that with no add-in PCI or PCI-e cards and only a 2.5" laptop drive, you could potentially move to a much smaller chassis, particularly if you shifted from the standard-sized 5.25" optical drive to a slim unit such as the Samsung SH-S082H.
The challenges of going to something this small add up when you realize you don't know how quiet or well-built many of the components are. Finding low-noise, high-quality ATX and SFX power supplies is much easier than looking for quiet 1U or FlexATX units. A few do exist, such as the SFX form-factor Seasonic Eco Power 300W and FlexATX form-factor Sparkle SPI220LE, but be aware of their drawbacks, particularly the fact that both actually tend to be noisier than many of their ATX counterparts at loads typically seen in a HTPC, which is exactly what we're trying to avoid.
For actual case recommendations, the Casedge DH-153, HEC 7K09BB, and several others are smaller and more compact than most of the cases in the primary all-in-one HTPC recommendation. They carry compromises here, and even with a PSU swap to a suitable lower-noise unit, their relatively poor internal airflow may find them to be more noisy than we'd like them to be.
Cost: $151.99 (4/27/2008) [Comparison shop for this item]
Total price: $604.29, not including shipping and handling (4/23/2008, no OS)
It may look just like the all-in-one HTPC box, but the lightweight front end ends up a little more than half the cost. It's still more than a comparable media center extender, but it's also much more capable and flexible. For a quick example, install a powerful discrete video card like an NVIDIA Geforce 8800GT 512MB, and you could have a formidable gaming setup in your living room.