Basically, "good" is a relative term. What's good for me is a $2000 AUD gaming monster machine with two GTX 580 in SLI. What's good for you is a $500 laptop to do your homework on and watch youtube.
If you want us to help design a pre-built computer for you, you have to tell us
EXACTLY what it is you need in a computer. In
your other thread, you only said "blu ray, plays games,tv tuner. Budget around $1500". All you need for that is an AthlonII X2 with a GTX 460 and 2GB of RAM, or even a Core i5-2400 with a H67 motherboard for the integrated graphics and 2GB of RAM. BluRay and a USB TV tuner are extras that you can get from eBay or similar sites with no problem.
EDIT: By exactly, I mean what kind of games you play. If it's things like Age of Empires or Counterstrike, you can go with integrated graphics. If it's things like Crysis and Modern Warfare 2, you need mid-ranged graphics.
Based on the other thread, you
do not need a $1500 PC, or even a $1000 PC. You also seem to have ignored my previous advice to use the PC-building sites
yourself, and
only then to post the results here for us to comment. That's possibly also the reason why the above posters have been unwilling to help you - because you're taking this forum and its members for granted.