Well, I'm not familiar with parts availability in Malaysia, but to get you started:
Since you are encoding, the AMD X6 is a good choice. More cores = better for encoding.
For the motherboard, any AM3 board will do but I would stick to the top tier brands like Asus or Gigabyte since they use solid caps and are generally of higher quality. Maybe consider one of the 880G chipset boards with the SB850 southbridge.
The TX3 cooler is a very nice HSF, but it's tall. Decide on a case before you decide on a cooler. Most HTPC cases are low profile. In that case, consider the Scythe Shuriken
or Coolermaster GeminII
low profile coolers instead.
What style of case are you looking for? A true HTPC case that looks like audio equipment or a standard tower?