Personal - Blue Screen while gaming

For the last few days, I have been having recurring problems while playing some games.  During the middle of the game, the computer will go to either a pure blue-green screen, or pure green screen, both with no text.  The computer will reboot and upon reboot the bios beeps 1 long, and 8 short beeps.  From everything I can find, this is a graphics card issue.  My hardware is as follows:

AMD X2 255 3.1GHz
Arctic Cooling Freezer 64Pro CPU Cooler
4GB Kingston Value Ram
ASUS M4A785TD -M EVO (On Board ATI Radeon HD 4200 GPU - (DISABLED in BIOS))
MSI N260GTX-T2D896-OCv2 GeForce GTX 260 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP
650W Power Supply
250 GB SATAII Hard Drive
Pioneer DVD-RW
LiteOn CD-RW
Linksys wmp54G Wireless Card
Logitech G15 Keyboard
Logitec G500 Mouse
ASUS 21" Widescreen Monitor
IOGear USB Hub
Windows 7 Professional x64

Upon reboot, I am presented with an unexpected shutdown report.  The contents of this report are below.


Problem signature:
  Problem Event Name:      BlueScreen
  OS Version:      6.1.7601.2.1.0.256.48
  Locale ID:      1033

Additional information about the problem:
  BCCode:      124
  BCP1:      0000000000000000
  BCP2:      FFFFFA8004CFD8F8
  BCP3:      0000000000000000
  BCP4:      0000000000000000
  OS Version:      6_1_7601
  Service Pack:      1_0
  Product:      256_1

Files that help describe the problem:
  C:\Windows\Minidump\070811-25178-01.dmp
  C:\Users\******\AppData\Local\Temp\WER-192552-0.sysdata.xml

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Looking through the event log, I cannot see anything that stands out.  I have a few errors upon boot, services not starting and a few other minor things, but right before the crash there are not any errors logged.  I have updated drivers, cleaned my PC out, ran a checkdisk, performed a defrag and even used a program called OCCT that will test for heat or other problems.  I ran the tests on both the CPU and GPU for 1 hour each, and the CPU reached a temp of 43 degrees and the GPU reached a whopping 86, but it did not crash the computer.  I am at my wits end with this, as it is annoying to be in the middle of a game and have it crash and corrupt your save games.