I would flash the BIOS to get HT. You shouldn't have to re-install the OS to upgrade the CPU, most of the time you have to do that when upgrading motherboards with different chipsets, but not processors (I went from a 2.6C to a 2.8C w/o problems under XP Pro). You may however have to re-install to get HT support in the OS, I ran into this problem once with a 2.6C, wouldn't see co-processors without re-installing.