The Dual core Regor is without a doubt a better option here.
The HD4250 is a lot better performer than the ION. Logically, if the IGP can handle pre-2005 games with mid to high settings, then surely it will play HD movies perfectly. Although I've heard that they still lag in some Bluray playback. For the safe side, get an HTPC GPU such as the passively cooled HD5450 for reassurance.