No picture on monitor

Hello,
I have built a new computer but can't get a picture to come up on the monitor pls help!!!

Computer is;
AMD Phenom Quad Core 9550
Gigabyte MA790X-DS4
MSI NVIDIA 512M GEFORCE 9600GT
ASUS 22" VW222U MONITOR
SHAW EXTREME 680 PSU
250 W.D. SATA HDD
20X LG DVDRW
2G Gingle DDR2 800

This is soooo frustrating!!
Everything looks to be installed correctly, when the power is on the fan on the cpu and graphics card all spin so there is power to them, and it sounds like the hdd is spinning up but no picture on the monitor...

Can any one help??