I'll second that. Only update the bios if it's absolutely neccesary. It might not be so bad these days, but a flash gone wrong could very well mean a bricked motherboard.
if it a motherboard from the past few years there should be program on there site or if you have the cd that came with the motherboard, to upgrade the bios
Never update a BIOS via Windows. Also do it manually in the BIOS itself.