What are the key ingredients to a quiet PC?

[persianxballer]

I have an HP computer right now, but I'n going to make my own in about a month. What types of things do I have to look for to make my future PC as quiet as my HP PC (practically no noise)?

 

[DoomUK]

If you can afford to splash out on a quality water cooling system, that'll obviously eliminate any noise from your case/CPU/GPU/etc fans...

 

[idiotec]

Check this out.

 

[Codeine]

A Thermaltake big water system with 2 Rads, and a few Vantec Stealth 120mm fans. That would be a great silent/performing system. Thats what i would do. But my system is a silent nightmare. I have 2 120mm 108-CFM fans and 5 120mm 125-CFM fans. I just worry about my OC and temps, rather then noise.