Hello Mohamad,
i recommend if you can buy the parts from newegg.com, they have all what you want for a good price,
below are some of the options for motherboard, CPU, Graphics, and Monitor
Motherboard:
Intel BOXDX58SO LGA 1366 Intel X58 ATX Intel Motherboard
243$
* CPU Type: Core i7
* FSB: QPI 6.4GT/S
* South Bridge: Intel ICH10R
* Number of Memory Slots: 4×240pin
* Memory Standard: DDR3 1600
* Maximum Memory Supported: 16GB
* Channel Supported: Triple Channel
* PCI Express 2.0 x16: 2
* Model #: BOXDX58SO
CPU:
Intel Core i7 920 Nehalem 2.66GHz LGA 1366 130W Quad-Core Processor Model BX80601920 - Retail
Customer Choice Award5x Winner of Customer Choice Award
279$
* Series: Core i7
* QPI: 4.8GT/s
* L2 Cache: 4 x 256KB
* L3 Cache: 8MB
* Manufacturing Tech: 45 nm
* 64 bit Support: Yes
* Hyper-Threading Support: Yes
* Virtualization Technology Support: Yes
* Model #: BX80601920
Graphics:
EVGA 896-P3-1255-AR GeForce GTX 260 Core 216 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card
204$
* Chipset Manufacturer: NVIDIA
* Core Clock: 576MHz
* Stream Processors: 216 Processor Cores
* Memory Clock: 1998MHz
* DirectX: DirectX 10
* OpenGL: OpenGL 2.1
* HDMI: 1 (via Adapter)
* DVI: 2
* Model #: 896-P3-1255-AR
Monitor:
SAMSUNG Toc T220HD Rose Black 22" 5ms HDMI Widescreen HDTV Monitor
249$
* Recommended Resolution: 1680 x 1050
* Viewing Angle: 170°(H) / 160°(V)
* Brightness: 300 cd/m2
* Contrast Ratio: DC 10000:1(1000:1)
* Display Type: WSXGA+
* Input Video Compatibility: Analog RGB, Digital
* Connectors: D-sub, DVI-D, HDMI, Component, Optical Out
* D-Sub: 1
* Model #: T220HD
Good Luck