I have an existing HTPC that does fairly well with an Asus board with an Atom / Ion, and handles full HD acceptably well thanks to VDPAU support in MythTV. I now need another one, so I've been looking around at the options. The Atom / Ion boards are still there, as are the AMD Turion's as so on.
In looking around I found a few fairly reasonable Sandybrdige boards with the H61 chipset. This seems to be a cost reduced version of the H67, and is missing a couple of PCI Express lanes and SATA 6GB/s ports. So I looked at the 1155 process options and the until the Sandybridge Celerons are released, the Pentiums seemed to fit the bill, again fairly reasonably priced compared to the i3 series, but with a few features missing. The important ones like the onchip Intel HD graphics and the memory controller which gives Sandybridge such high memory bandwidth.
So I went for an Asrock H61M-ITX board and an Pentium G620 for just over £100, add 4GB of DDR3 memory and that took it to £120, which I think is less that the Atom board cost a couple of years ago.
Performance wise I was very impressed, with better memory bandwidth scores than my i7 950!
I went for the same case as the previous one, a cheap unbranded ITX case with a 250W PSU. I quickly decided to make the same modifications to the case as with the previous one, namely getting rid of the two noisy fans. There is an 80mm fan on the front and a thin 80mm fan in the PSU.