By default, most newer AMD chipsets with integrated HD video have AMD Crossfire support enabled. To allow for secondary cards to display on multiple monitors it is necessary to disable AMD Crossfire. To do this, open the AMD VISION Engine Control Center and disable AMD Crossfire (usually located under Performace). Once disabled, it is recommended to reboot the computer before you configure your display settings and setup your multiple displays.
This is normally ONLY an issue in Windows Vista/7.
Motherboard: MSI A55M-P33
Processor: AMD AD3300OJHXBOX A4-3300
Memory: 4GB DDR3
HDD: 500GB SATA
ODD: DVD±RW SATA
Video: Asus EAH5450 PCI-E 1GB DDR3