No Sata, intermitantly just locks up and reboots on it's own.

Random computer reboots can be difficult to diagnose. Try the following:
1) Check event viewer for messages that could be related. (Control Panel >Administrative Tools >Event Viewer) These could point you in the right direction.
2) PC could be overheating. Many motherboards have a utility you can install to display the CPU and motherboard temperature. I have read the maximum operating temperature for the AMD 9850 is 61C (142F). You can also see the CPU and motherboard temperature via the BIOS. If heat is an issue try installing extra or more efficient case fans, run the PC with the side panel off or maybe get a better heatsink/fan for the CPU if you are using the stock AMD offering.
3) If the inside of the case fairly clean? I see many PC's full of dust which prevent the cooling fan working efficiently causing the PC to overheat and reboot. If your CPU heatsink is covered in dust give it a careful clean...it makes a lot of difference.
4) Check for loose cables. Reseat any that look suspect.
5) Remove one of the harddrives and see how it runs. If fine take it out and try the other. If fine try them both. (this may be difficult if one of them is your system drive) If one appears to be at fault test it in another PC and if the fault follows the drive take it back for a swap.
6) Could be that your power supply is not powerful enough. What wattage rating is your Power Supply? You can see this on a sticker on the PSU but you will need to open the case to see it. Your CPU sucks upto 125 watts and video card up to 150 watts depending on model. Depending on the exact model of video card I would think the minimum PSU rating you would need would be 550-650watts....more to be safe. Maybe adding the harddrives just pushed the PSU over its limit?
7) Computer reboots and freezes are often related to bad memory. Could be that when you installed the HDD's a bit of static electricity found its way to the RAM? (unlikely but stranger things have happened) Do a memtest. Maybe take out one stick of ram and test. Then swap over and use the other stick and try and isolate a bad stick. Test each stick for hours, not minutes. When I test ram I drop down the size of the pagefile and run heaps of programs to ensure the ram is being fully utilised and tested.

Good luck and please reply with any comments.

Go to bios settings,check Hard disk related option
If you want to install xp then you have to change this setting from AHCI or SATA to Ide