core i7 920 - quiet

Hi all

I'm planing on building a pc based on an Intel Core i7 920. I need a configuration that in the first instance runs very quiet and if possible anyway allows for light overclocking (~3GHz).

I'm quite sure about these components
- Intel Core i7 920
- GIGABYTE GA-EX58-UD3R

Not so sure with:
- RAM: Kingston, Crossair, ...??
- Graphics: silent, not that important (although I do like games I prefer a quiet system)

A lot of questionmarks with
- Case?
- Fan?
- PSU?

important:
I need the pci slots so nothing should cover them up (like huge fans etc.).

And yet another question:
Can PCI-E x1/x4 card be used with PCI-E x16 slots? Are the PCI-E 16 slots usualy graphic card exclusive?

I never have built a pc before - just spent hours and hours fumbling around in them - and am very glad for every hint, info you could give me.

Many thanks for your help!

Nept