Custom build.

[N!ck]

The Samsung one is slower than the WD one. It may not use as much power but it's sacrificing speed.

It actually performs very similarly, which is amazing as it only uses a 5400rpm spindle speed. http://www.harddrivebenchmark.net/high_end_drives.html the samsung gets 547 and a WD5000AAKS2 (possible a revised model of the WD5000AAKS you posted?) gets 559.

[Jahova]

It's fine, nothing needs to be changed now. I may think about that graphics card, that's all.