To do things like this you are better off running a LAN with VNC on Linux and Windows. Use VNC to connect a virtual terminal and then you can flick between widows and Linux by using the virtual desktops. Works well.
Then you can use wine to run the VBA - VB code of the Linux node
Linux tries to use the HD as little as possible. The data is store in RAM and when the user is idle the data is written to the HD. This is why you hear the harddrive churn when you are not doing anything..
Why would you wish to boot XP anyway?
You can always use tools that allow windows software to run on the Linux system.
Wine and XWine are an example of this.
Note that this is not an emulation but a Kernel messaging clone. Because the Linux Kernel is more productive than the windows...
You can use the CLI (or terminal) to login to root.
use the command su like this:
go to K | Terminal | Gnome-Terminal (or any other)
you will be presented with
[email protected] user/#
[email protected] user/# su
Enter the password for the root acount.