As stated before, SolidWorks 2012 software (including CAD, Simulation, Sustainability, and Enterprise PDM) is the last release that will run on Windows XP. SolidWorks 2013 will NOT INSTALL on computers using Windows XP.
This action is being taken as a follow up to Microsoft’s retirement of the Windows® XP operating system in April of 2009.
SolidWorks recommends moving to Windows 7 as the preferred operating system for the next releases of SolidWorks software. At this time the ideal approach is to upgrade your computer hardware to 64bit technology and use the Windows 7 64-bit Operating System.
For additional information please refer to the SolidWorks System Requirements page