Normally, I would do all you suggest except that the fault is internitent - e.g. FS2004 was a no-go but since this morning it runs absolutely fine. That's what I don't get.
The PC is a Dell 2400 Opteron, Celeron, Intel o/b graphics with 512 RAM. Running XP Pro SP1 with Zone Alarm and AVG only in the Start Up list.
PSP