i think you find that the speed of the ram on the 4600 makes up for it as the fx5600 that msi make only actually runs at 400 mhz i know i had one from msi. Also the 4600 has better fill rate and operations a second but i am not sure.
3.2ghz Pentuim 4 HTEE (800 FSB),1024 mb ram,Geforce fx 5900
Creative 5.1 digital ,DVD/DVDRW
1 case fan , 500 watt power supply