Something's wrong when the refurbished HDD is more expensive than the CPU, and the Diablotek PSU is $20. On an early AsRock mobo (back then they were horrible) no less.
On this budget (~$250 from what I can see), you just cant build a decent PC. I wouldn't trust this thing as a HTPC.
Most advice I can offer is throw some more cash at it, or look for pre-built options. Just at this budget, there is nothing you can really do.