I've had the new system for the past few weeks now, but I've been getting BSODs quite recently now. They started out as one offs which I thought would go away and eventually became quite regular (every day and then every hour, right up to sometimes Blue screening right after restart), so I thought it could be because I overclocked the cpu (I overclocked to 2.6GHz after about a week, maybe a bit too quick, although it survived prime 95 for 9 hours before one core gave out), so I downclocked the processor, until eventually I just reset the bios to all default settings.
This hasn't solved the problem either, so after doing a bit of research, I found out it could be the nvidia hardware firewall. So I've now uninstalled that and have read that I should upgrade to the latest nforce4 drivers as well.
I will try that now and update later to say whether or not it's fixed.
Just thought I would share this info with everyone in case anyone else is having similar problems, then it could be the nvidia firewall.
If it doesn't solve the problem, then I'm going to be very stuck!
My New System: Opteron 165
2GB OCZ RAM
1x250Gb Samsung spinpoint (8MB cache
1x120GB IBM/Hitachi 7200rpm (8MB cache)
1x200GB Western Digital 7200 rpm
1x300GB Maxtor 7200 rpm (16MB cache)
Windows XP Pro SP2