Windows 7: BSOD while browsing net and watching movie

Dear All,

This is my first experience of random BSOD.
I have no clue how to read it, tried to google and was led here.

I just got the BSOD Dump and System File Collection app.
But I got another BSOD while running it as administrator.

Another try and finished it.
I looked for performance monitoring report, but could not save it.
Only an "Option" and "Exit" tab were among the choices in "File" tab.

Another BSOD went while I was checking online for solutions.
This time, after reset button, there were 3 short beeps.
Then a message showed insert "USB BIOS flash..."
It would just go in a cycle, it was late so I decided to sleep, hoping my PC will POST in the morning.

Also, in the previous days, while playing League of Legends, the game suddenly crashed.
A message appeared showing a "Bug Splat"

Anyway, please see attachments.
I hope they are useful.

Thanks!
Edu



System Specs: (built on June 2011)
Athlon II X3 400
MSI 880GM-E43
Kingston Value RAM DDR3 1333MHz 2gb x2
PowerColor HD 6770
Western Digital Caviar Blue 500gb
SilverStone ST50F-ES 500w
Windows 7 x64 auto updated

Could anybody suggest what to do?
Do I need to reformat my HD and have a clean install of Windows7?
Please help.