Brand new system hanging please help!!!!!!?

System configuration ASUS EP45CDS3R mother board Intel Core 2 Duo Quad 2.33ghz Transcend 3GB RAM DDR3 1333mhz FSB 500 GB Seagate SATA LG DVD R/W 19" AOC TFT LCD NVIDIA 9600GT 512MB DDR3, the problem is that when i would be using the system reading doents it would hang involuntarily while transferring a folder 6 gb in size it hanged midway during the transfer while playing NFSMW it hanged after 15 min of game play the smps is of 500watts. The dealer said that it might be because of the smps since the power supply might not be sufficient for the above configuration but i doubt it might be the ram because while playing NFSMW it restarted midway into the game because had it been a smps problem then the system should have shut down completely but it restarted some of my gaming friends suggested that it might be the ram acting up.Does anyone have any suggestion as to what to do about this problem?