Please help my with my BSOD. Happens multiple times a week.

Operating System Windows 7 x64
Computer Type Desktop
OS Service Pack SP1
Internet Explorer Version IE9 FF8.0.1
DirectX Version DX11
CPU Type and Speed Intel 5300 Dual 2.6GHz
CPU Cooling Out the box
CPU Idle Temp 33°c
CPU Load Temp 49°c
Motherboard Chipset ASRock G31M-S R2.0 BIOS v2.0
System BIOS Revision P2.00
System Memory Type 2 x 2GB Corsair XMS2
System Memory Speed Default
System Memory Clocking Default
Video Card Type and Speed Sapphire Radeon HD 5670 512mb
Video Card Cooling Out the box
Video Card Temperature 40°c
Video 3DMark Score 1495
Power Supply Unit (PSU) 500W Generic Bag of sh*te
Computer Monitor AOC 19"

Sound Card Generic
Speakers Logitech Stereo, Rear Speaker: Janice
Headset/Microphone A very cheap Philips set. Bargain!
Hard Drive Samsung F3 320GB Samsung F3 500GB & Maxtor 60GB IDE
Optical Drives Samsung DVD-RW SH-S222A
Keyboard and Mouse MS 600 Key. Ms 4500 with a purdy blue light. Squeak!
Network Adapter Say Hello. Good Network!
Printer Epson SX210
Network Speed 100mb, they tell or sell me
USB Controller Me. plug in, plug out.
Gaming Console What? You think I got time to play?
Anti-virus Software ESET AV, Mbam, WinPatrol, Win 7 F/W
Productivity Suite No productivity suite, but a nice 3 piece one.
System Install Date Aug. '11
Computer Skill Level Self-Taught Expert
Windows Experience Index 5.9
Favorite Game Pass the Zimmer
Favorite Application Zam-Buk Embrocation