Вот определение, которое тебе может пригодится:
typedef enum _SYSTEM_INFORMATION_CLASS {
    SystemBasicInformation,
    SystemProcessorInformation,
    SystemTimeOfDayInformation,
    SystemPathInformation,
    SystemProcessInformation,
    SystemCallCountInformation,
    SystemDeviceInformation,
    SystemProcessorPerformanceInformation,
    SystemFlagsInformation,
    SystemCallTimeInformation,
    SystemModuleInformation,
    SystemLocksInformation,
    SystemStackTraceInformation,
    SystemPagedPoolInformation,
    SystemNonPagedPoolInformation,
    SystemHandleInformation,
    SystemObjectInformation,
    SystemPageFileInformation,
    SystemVdmInstemulInformation,
    SystemVdmBopInformation,
    SystemFileCacheInformation,
    SystemPoolTagInformation,
    SystemInterruptInformation,
    SystemDpcBehaviorInformation,
    SystemFullMemoryInformation,
   SystemLoadGdiDriverInformation,
    SystemUnloadGdiDriverInformation,
    SystemTimeAdjustmentInformation,
    SystemSummaryMemoryInformation,
    SystemNextEventIdInformation,
    SystemEventIdsInformation,
    SystemCrashDumpInformation,
    SystemExceptionInformation,
    SystemCrashDumpStateInformation,
    SystemKernelDebuggerInformation,
    SystemContextSwitchInformation,
    SystemRegistryQuotaInformation,
    SystemExtendServiceTableInformation,
    SystemPrioritySeperation,
    SystemPlugPlayBusInformation,
    SystemDockInformation,
    SystemPowerInformation,
    SystemProcessorSpeedInformation,
    SystemCurrentTimeZoneInformation,
    SystemLookasideInformation
} SYSTEM_INFORMATION_CLASS;
Вот пример, как можно работать с функцией NtQuerySystemInformation 
http://subscribe.ru/archive/comp.soft.prog.hitech/200311/01163215.html . Посмотри главу "Дампер процессов"