An i5 2300 on an H67 board with an HD7850 is pretty competent platform for HTPC use, particularly for secondary HTPC duties.
My primary HTPC is an i3 530 on an intel H55 board which I just recently updated the GPU to an EVGA 750 Ti. I have it set to Jinc for madVR chroma and pixel scaling. The 750Ti is a very quick HTPC GPU and it would perform even better on an H67.
My primary personal workstation is an i3 2100 with a GT 545 nowhere near the graphic horsepower of the 750Ti. This box is running an H67 Intel board. It is more than adequate for most HTPC tasks. I had matching GT 545s in both the Clarksdale and Sandy Bridge systems and the GT 545 performed markedly better on the Sandy Bridge. Leads me to conclude the H55 PCIe bus is not very well optimized. On the Sandy Bridge workstation I often have cable tv news running in a WMC window while doing all my other PC tasks with no slowdown at all. In fact I have an HP extender keyed to this box as well and I don't sense any slowdown from the extra load.
While newer intel stuff has many advantages the Sandy Bridge stuff is plenty quick and energy efficient. An i5 2300 with a mid-level discrete GPU is in my opinion more than adequate to handle all but heaviest HTPC work loads. I have another i3 2100 box with a Ceton in it, that I am going to consider repurposing. It is avaliable as it looks like I am going to end up using SiliconDust stuff exclusively. I will probably install an SSD, and a GT 750Ti in an appropriate case and make it my primary HTPC in the next couple of months. I have and HD7790 floating around here but the performance and energy consumption of the 750Ti is pretty much unmatched it its class. Bothe he HD7790 and the 750Ti are a healthy GPUs but not up to 7850 performance.
Personally while I really like what madVR does, I don't see its value unless you are using a really big display. I only use madVR day to day on my primary HTPC which is feeding my 92" Mitsubishi DLP.
Mits WD-92840 92" DLP - Lumagen Radiance XS, Martin Logan Motion 40s, Ascend Sierra 2s
Older 58" Panny Plasma -DVDO DUO, JBL Studio 530
Pioneer AJs, PSB Images, Usher S520, JBL HLS-610, Definitive SM45, MusicHall Marimba