BSOD when idle after win 7 update

Hello, i recently updated my OS to win 7 and since then i get more and more frequently bsod's when the machine is idle (e.g. when i leave it on and get back). The computer just restarts and when i'm back and running it prompts me that there was a critical kernel-power failure (Event ID 41). I'm running an older machine with updated parts here and there, i intend to get some new hardware (thought of mainboard & Power supply) but I want to invest in the right parts so i want to figure out if there is indeed a hardware issue (what i doubt since these bsod's startet with win 7).
Anyway my system is:
Mainboard: AUSTeK P5K-E
Cpu: Intel core 2 Duo E8400 @ 3.00Ghz
Ram: 3x2Gb DDR2 by MDT
Graphics: Radeon Power Color HD 6770
HD: Samsung HD501LJ 500Gb
Lacie External Drive 500Gb
Also there are alot of usb devices plugged in (Headset, mouse, razer keyboard, Usb hub etc).
I really hope it's nothing serious and i can get helped, thanks alot in advance.
Regards, Perks

The basic things to try:

1/ Offline scan for viruses/malware: http://windows.microsoft.com/en-US/w...fender-offline
2/ Mem+ test: Memtest86+ Memory Testing
3/ Remove Asus ATK0110 ACPI Utility (a known BSOD maker in Win7). Also a part of the Asus PCProbe and AISuite Utilities

Let us know how you go.

Hope this helps.