Yes the CPU does seem like overkill and when I started I went for the 4850e and then discovered that with the onboard graphics the HT speed is very important.
So I ended upgrading the cpu in my HTPC. If the 240e were available that would be better from a thermal point. You can get less of a cpu just watch the HT speed if you plan to use the onboard graphics…
Even though it seems like overkill, the cost is such now that there's not much point going much lower. £37 is what I paid. And that's the lowest AM3 cpu I could find. Should be able to fiddle with ffdshow without strain. Or have it running more or less as idle and keep the temp and power down.
Anyhow, all arrived and waiting to be built up. Will let you know how it goes.