memory integrity test error and BSOD Memory management Error

Hi there,

I upgraded my Inspiron 545 to Windows 7 64 bit and upped the RAM as well to 8 gb.

I am getting Blue Screen of Death now quite often - Memory management Error.

I ran the  Diagnostic test and got a couple of memory integrity tested that failed - Memory Ground Test, and March B test.  The error codes are 2000-0123 and Error Code 2000-012.

Any advice or suggestions on where to go from here? 

Hardware specs here:

DELL Inspiron 545 Minitower with Black Bezel    Intel® Core™ 2 Quad-Core Q8200 Processor (2.33GHz, 4MB cache, 1333MHz FSB) and I upgraded to Windows 7 64bit to install 8GB ram (max for my motherboard.)

2 x Komputerbay 4GB 2X 2GB DDR2 800MHz PC2-6300 PC2-6400 DDR2 800 (240 PIN) 1.8v DIMM Desktop Memory