These are all errors that affect your memory - so most likely they're a device driver/system service issue. But, numerous different error messages frequently seem to point to hardware issues.
The only thing of note that I can see is your PSU - it appears to be a 400 watt unit (which is awfully anemic for today's hardware).
Beyond that I'd wait for H2SO4's advice.
Summary of the memory dumps:
Code:
Built by: 7600.16385.amd64fre.win7_rtm.090713-1255
Debug session time: Fri Oct 23 13:26:52.191 2009 (GMT-4)
System Uptime: 0 days 0:24:04.752
BugCheck 3B, {c0000005, fffff8000288b4ec, fffff8800876bfe0, 0}
Probably caused by : ntkrnlmp.exe ( nt!KiSystemServiceHandler+7c )
DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT
PROCESS_NAME: iexplore.exe
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Built by: 7600.16385.amd64fre.win7_rtm.090713-1255
Debug session time: Fri Oct 23 13:02:20.983 2009 (GMT-4)
System Uptime: 0 days 1:11:52.544
BugCheck A, {0, 2, 1, fffff800028a4c3a}
Probably caused by : ntkrnlmp.exe ( nt!AlpcpQueueIoCompletionPort+1aa )
DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT
PROCESS_NAME: iexplore.exe
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Built by: 7600.16385.amd64fre.win7_rtm.090713-1255
Debug session time: Fri Oct 23 16:17:16.417 2009 (GMT-4)
System Uptime: 0 days 2:49:47.352
BugCheck 1000007E, {ffffffffc0000005, fffff8800418affb, fffff8800593c658, fffff8800593beb0}
Probably caused by : dxgmms1.sys ( dxgmms1!VIDMM_GLOBAL::ReferenceAllocationForSubmission+ab )
PROCESS_NAME: System
DEFAULT_BUCKET_ID: NULL_CLASS_PTR_DEREFERENCE
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Built by: 7600.16385.amd64fre.win7_rtm.090713-1255
Debug session time: Fri Oct 23 11:09:09.176 2009 (GMT-4)
System Uptime: 0 days 0:54:32.111
BugCheck 19, {3, fffff80002a0aad0, fffff80002a0aad0, fffff80002a0aed0}
Probably caused by : Pool_Corruption ( nt!ExFreePool+536 )
DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT
PROCESS_NAME: iexplore.exe