Followup: What's the difference between entertainment PC & gaming PC?

In my original post, I emphasised the importance of quietness as the requirement or expectation to the to-be-built PC.

Instead of putting the new PC together, I replaced the case fans in my noisy PC (P4-2.4G/1G RAM) with scythe 80mm as recommended here.

The noise level came down drastically. At the same time, I bought the Tuniq Tower 120 as well. This thing is big. I didn't replace mine as I almost bent the pins when putting the CPU back to the socket. If I couldn't save the CPU, definitely the new PC would be the only choice.

In the meantime, I will do more research on the video card and memory.....

thanks for all the advice ..... my PC is much quiet now and that is what matters.