i have an issue, we use ubuntu and for VBox as a Virtualizers ,

i have installed winxp as a VM and wanted it to make a dual screen boot-up. i executed a VBox command to make it dual boot... as one as primary screen and other is secondary screen. so when i execute commands both the screen open up in a single monitor. but my requirement is one screen should come in primary monitor and other one in a secondary monitor which is connected using VGA port.
pls help me on this.