For others having perhaps the same problem, this condition works (see WindowsBuild numbers):
Version9X OR VersionNT64 OR ((VersionNT > 600) OR ((VersionNT = 600) AND (WindowsBuild = 6001) AND (ServicePackLevel >= 1)) OR ((VersionNT = 600) AND (WindowsBuild =6002) AND (MsiNTProductType = 3 ...