Morpheous wrote:Power... look out for PSUs that give substandard 12 volt rail Amperage. 18A is running a P4 fine here- older PSUs (Powering Pentium 2/3) needed buckets of +5 and no +12, but P4s switched to 12v rail.
Apart from that- if you can get to a desktop, install Motherboard Monitor 5 and check the voltages from there, and/or temps.
Dust won't help either

Though somewhat true, the +12V is still far less important than the +5 and +3.3 for P4 mainboards (Of this I was informed by extensive technical knowladge coming directly from intel, but however is FYEO (in this case thus FMEO and I can't post that shit:p)
Anyway, get your freaking soundcard to another PCI slot ASAP! Your videocard should be on his own completely, no shared IRQ's there. Usualy the best thing is to put the soundcard in the last PCI slot, but it can differ per mainboard.
Also - your Raid controller - try getting it on a not shared IRQ aswell, if not for stability, it will increase performance. And yes the IEEE 1394 is firewire - nic and the fireware shouldn't matter to much on sharing IRQ's, but if its possible, its always best to have as much hardware on a unique IRQ adres.
I know IRQ's are far less important now as they where in the days of DOS/win9x systems, but they are still important for stability.
Hope this solves atleast some of the problems, or at the least increases overal performance.
A small sidenote - normaly looking for instability, I start looking for cpu/memory problems, take a good look at your mainboard to, especialy the transistors - one of them might have popped, the system will simply continue to work with a few popped transistors, but it gets far less stable, and less the more they are popped (popped - means they are leaking, you can see this at the top of them, they stop being functional when they leak (duh))
I recommend the following tool for some testing: Burnintest
See:
http://www.passmark.com/download/
Its one one of those tools that help you identify problems with certain aspects of your system.