I need to build a good gaming computer for 1000$

MOBO:
http://www.newegg.com/Product/Produc...82E16813128059 95$
http://www.newegg.com/Product/Produc...82E16813127030 180$

CPU:
http://www.newegg.com/Product/Produc...82E16819115028280$
http://www.newegg.com/Product/Produc...82E16819115017 280$

Graphic Card: any where from 100~300$

Sound Card: less than 50$

Hard Drive:
http://www.newegg.com/Product/Produc...82E16822136012 170$
http://www.newegg.com/Product/Produc...82E16822136075 50$

RAM:
http://www.newegg.com/Product/Produc...82E16820145043 121$

Fans: less than 20$
Case: less than 100$

Power Supply:
http://www.newegg.com/Product/Produc...82E16817182017 50$

DVD drive: less than 50$

Questions
Do I need more than 550W to run a quad core and a 8800GT?
How many fans do I need? I heard 8800 GT overheats very easily.
280$ for 3.0ghz Duo Core or 2.4ghz Quad core?
Can you build liquid cooling? Is it hard? How much will it cost? Is it worth it?
When does Geforce 9 Series comes out? Any time soon?
Is there a 8800GT 256 MB?
10,000 RPM or 7,200 RPM for HD?
Can 2 cheaper graphic card in SLI beat one 8800GT?
XP or Vista?

Please answer the questions and pick a good case for me, and to give you an idea how much my PC suck right now...

Edited: New questions

Should I wait for the 9 series? Will the 8 series lower the price when 9 comes out?