Re: Random Restarts
At this point, it is still hard to pinpoint where the problem resides. What you could've done is right after the reformat, reinstall Windows XP and just the bare essentials like driver updates. Run if for awhile to see if errors occur. If not, then install virus protection and firewall, then go online to get Microsoft updates. Test that out for a week to see how that goes. Then install Office and test that out and so on and so forth until you find the culprit. If it crashes on you prematurely, it may be hardware issue.
Try installing a diagnostic utility such as Fix-It Utilities which includes powerful diagnostic tools to aid in finding problems with your system. SMARTDiskCheck Hard Disk Failure Early Warning System notifies you when your SMART-compatible hard drive motor is having trouble, before the drive fails and your data is toast. PCDiagnostics checks and reports on your installed system hardware including memory, hard drives, serial and parallel ports, video and sound cards, DVD/CD drives, and more. It pinpoints errors and identifies possible causes of trouble. SystemExplorer scans your system and provides a complete list of system statistics. SystemMonitors keeps an eye on your system resources and warns you when monitored resources reach critical levels. ErrorTracker logs all Windows errors messages to assist in troubleshooting system problems.
Those will help to determine hardware faults and possibly pinpoint exact replacement if necessary.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?