After looking and your stop code, this is what i came up with.
You have a device that is trying to access memory space 0x4c616205 on IRQ 2 [IRQ 2 covers IRQ 8-15 so it could be a mouse, hard drive, optical drive, graphics card] so it can write to it. The instruction came from memory space 0x8baa8db1.
The first thing you want to do is check to make sure all of your drivers are updated to version supporting windows 7. If they do not have windows 7 compatible drivers, you can try to install vista drivers in compatability mode. If that still does not work you may not have all windows 7 compatible hardware.
You also might have some bad ram.
Let me know your results.