Due to the way applications install within an operating system’s registry, it is unlikely that the billing application in question would be accessible in an external format from within a new operating system. Instead, what would be advisable would be to consider the two following options.
The first method which treefrog07 mentioned is to create a dual boot, or multiboot configuration between Microsoft Windows XP and Windows 7. The first step, as you also stated, is to ensure you have a separate location for each operating system you intend to use. In this scenario you will want to have one partition for Windows 7 and a second, separate, partition for Microsoft Windows XP Professional. Just as an added tool, Microsoft has a helpful video of how this process is performed here
. Another great resource is the multiboot step-by-step guide Install more than one operating system (multiboot.)
However, with that said, perhaps the easiest way to run Microsoft Windows XP within Windows7 is through Windows XP Mode and Virtual PC
just as another member of this thread pointed out. Windows XP Mode and Windows Virtual PC, available on Windows 7 Professional and Windows 7 Ultimate, allow you to run multiple Windows environments, such as Windows XP Mode, from your Windows 7 desktop. For those who do are not currently running Windows 7 Professional, Windows 7 Enterprise, or Windows 7 Ultimate, there is an easy upgrade path to Windows 7 Professional or Windows 7 Ultimate through the Windows Anytime Upgrade
Please note that Windows XP Mode is a virtualized environment and is not recommended for graphically intense applications. If utilizing Windows XP is contingent upon the use of a graphically intense piece of software, it would be advisable to consider the previously mentioned dual boot environment as a more successful path.
Windows Outreach Team – IT Pro