LG M1 dual express

Dual Core 1.83Ghz
Geforce Go 7400 512 Mb overclocked from 450 to 540 mhz (yes it's possible!)
external monitor:Samsung Syncmaster 226bw 22"

I'm planning to build my own gaming rig,but I have to know which components I can purchase locally,and which ones I'd better to buy online( Amazon,Newegg,...)
My core dream config:
Mobo: nforce 780i for future SLI
CPU: Q6600 (for a potential OC)
GPU:High end Nvidia (maybe gtx260/280 will be soon more affordable?)
A convenient PSU for such a config...
What about the case?
mr_listener kindly refered to the Gigabyte solution (Tornado computers in Sofitel area)but it looks like the price can go pretty high.
I searched for other brands,sadly no official resellers here in Doha for MSI,XFX,EVGA,Asus,...
So I need QLers advice on this.
Thanks.

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