FYI - the latest version of MC now uses LAV's / QuickSync HW Acceleration for the HD 3000 (and other Intel IGP). I have been running my i7-2600K based HTPC with the HD 3000 for a couple of months with few issues and the addition of the HW Accell option will ensure lower end CPU's have little difficulty as well.
Couple of comments on getting the best from the HD 3000:
1) in madVR I needed to change the Scaling algorithms to not use the ones with "TAPS" (eg Lanczos or Spline) but appart from that have not changed any other setting
2) ATI and nvidia have mostly fixed the issue of the HDMI connection being dropped or the EDID information being changed when the receiver is OFF or switched source. I found that in my AV config, the HD 3000 would tend to drop the HDMI audio as the default connection in this case. I reinserted my old DVI Detective Plus (keeps broadcasting the EDID info) and it is rock solid.
So..... if you were building a new dedicated HTPC at present, I'd certainly recommend just using the HD 3000 over adding a separate GPU. It works well and keeps heat, noise etc down.
Very happy!