STEP 7 V5.5 is a 32-bit application that can be used with the following operating systems:
1:MS Windows XP Professional SP2 or SP3
2:MS Windows Server 2003 SP2 / R2 SP2 Standard Edition as workstation computer
3:New as of this version: MS Windows 7 32 Bit Ultimate, Professional Enterprise (standard installation). The Windows XP mode under Windows 7 has not been approved yet.

STEP 7 has not been tested for the following operating systems; use at your own risk:
1:MS Windows XP Professional with SP1
2:MS Windows Server 2003, SP1, SP1 R2
3:MS Windows Vista Ultimate, Business and Enterprise
4:MS Windows Server 2008 std. Edition SP1 and SP2