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Instead of a dual boot I would run Virtual PC it is free from Microsoft.Click on me
The advantage of this is you can run xp in virtual mode and switch between windos 7 and xp without a reboot.
If you have a video card that lets you run another monitor then you can run XP on one monitor and Win 7 on the other.
Why do you say you cannot use XP compatibilty mode?
If an older program doesn't run correctly, the first, and easiest, thing to try is the Program Compatibility troubleshooter. It can automatically detect and fix common problems that prevent older programs from installing or running correctly.
Open the Program Compatibility troubleshooter by clicking the Start button Picture of the Start button, and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Under Programs, click Run programs made for previous versions of Windows.