PC Randomly Crashing/Blue Screens. Performance Is Lowered

[Problem224]

Hello, everyone.
About a week or so ago, my PC started to randomly crash and blue screen. Also, performance in games has lowered significantly. I would be grateful for any help. My specs:
Processor: Intel Core i7 CPU 920 @ 2.67GHz (8 CPUs), ~2.7GHz
Memory: 3062MB RAM
Hard Drive: 489 GB
Video Card: XFX ATI Radeon HD 5770
Operating System: Windows Vista Home Premium
Motherboard: Asus P6 Deluxe V2 1366

 

[Proximon]

http://www.tomshardware.com/forum/forum2.php?config=tomshardwareus.inc&cat=31&post=292686&page=1&p=1&sondage=0&owntopic=1&trash=0&trash_post=0&print=0&numreponse=0&quote_only=0&new=0&nojs=0

Any utilities I mention can be found there.

Let's start with temps, because they are easy. DL HWMonitor and report the CPU core temps and the GPU temps.

Also, list the following:

PSU
Anti-virus
Firewall


Then while you wait for a reply run memtest from the boot disk.