Where's the bottleneck? HTPC

I built a computer for a friend of mine using http://www.newegg.com/Product/Product.as...6856101117 and a http://www.frys.com/product/7095831?site...IN_RSLT_PG with an I-5 2500k and http://www.frys.com/product/6897836?site...N_RSLT_PG; using ubuntu x64 as his OS.

I'm about to build my own and am not satisfied with his performance, thus the reason I am asking for advice on where the bottleneck might be.

I am open to suggestions with reasons that support.
Future build will include win7 x64 ultimate lightened down Samsung, Vertex, or Crucial SSD, 8GB Ram Not sure if I will go 1800 for spd or not, GB Lan mobo, and an AMD 7xxx series 1GB or higher GDDR5 OC'ed GPU (haven't quite narrowed it down yet), due to the most up to date UVD3 and so on.

The goal is for each component to provide silky smooth response regardless of workload, while up-converting all forms of media (primarily streaming via 1channel, watchseries, and icefilms). Those darn compression artifacts really tick me off!

I am currently running a Presario Athlon 64 170u with 4GB 800 Hz Ram, Zotac GF-210 1GB, with win7 x64 Ultimate that's been lightened up.


Your' help is greatly appreciated!