‘Windows XP Mode’ could not be started because there are not enough system resources or memory in your computer. You can shut down other virtual machines or close open applications and try again.
If you're running Windows 7 and try to install Windows XP mode, you might run into the error "'Windows XP Mode' could not be started because there are not enough system resources or memory in your computer. You can shut down other virtual machines or close open applications and try again." You'll need to find the app causing the problem. You can use msinfo to figure out which apps are resource intensive.
Did you know…?
Windows 7 sports tons of new features and surprises that have gotten little to no fanfare.
Did 
you know that Microsoft has updated the Windows Calculator with Windows 7 with some really new and useful features? Previously, most of these features often required you to open Excel or use some website to solve the problems they address. The calculator sports new features including Unit Conversion, Date Calculation, Mortgage, Vehicle Lease, Fuel Economy (in both MPG and KM no less!) You can find the different options under the View menu after opening the calculator up. See screenshots below for examples of what the calculator can do.