Xeon Workstation BSOD after upgrade to Win 7 Pro.

I built this system in 2006, it had been running XP x64 without a problem, the s/w the customer uses, Solidworks, required the PC to be upgraded to Win 7 Pro x64 in April. He has been having consistent problems even after replacing the hard drives, the power supply and checking the ram.

Here is the config:
Supermicro X7DA8 (latest BIOS)
2 x Xeon 5160 CPUs
8 x Mushkin 2GB FB-DIMM
PNY Quadro FX 5000
2 x Adata 256GB SSD
1 x WD 500GB Green Drive (Backups)
Seasonic X-1050 1050W PS

No Overclocking!

I recently reloaded the system (again) after installing the SSDs, I used minimal drivers, just the audio and suggested Nvidia drivers recommended by Solidworks. I did not load any chipset drivers because I found that caused serious file transfer issues.

The system randomly gets BSOD, sometimes when working, sometimes when the PC is idle. Also after a fresh load of Windows that I did offsite, I had no issues while loading the PC (well none that I could not address) but once I returned the PC to his office, it BSOD the first boot. We removed his UPS and the PC booted fine, but the problems were just beginning. My guess is the hardware is just not compatible with Win 7 since we had zero issues with XP. Also I did test the RAM, but I can do it again.

Thanks for the help, this one has been driving me crazy.