Applications that don't work well with dual-core don't immediately crash the system. I have a wireless driver that doesn't like my Opty 165, and once the driver starts up, it generates a weird sine wave-like pattern (but a bit flatter) in the Task Manager CPU Usage History graph that continues for a while until the system crashes like 5-40 minutes later. In Windows XP, I had this problem too, but one of the fixes (either the XP DC fix or the AMD driver) resolved the problem. Then I switched back to Windows 2000, and the problem started again. Since I couldn't install either fix this time around, I had no choice but to disable one of the cores, which you can do by changing the ACPI Multiprocessor driver to ACPI Uniprocessor in the Hardware control applet.