It may already have the latest BIOS version installed, so check this before updating the BIOS.
You only really need to flash the BIOS in two scenarios:
1. The CPU you'll be using needs the newer BIOS version to function
2. There is some must have feature that only a newer BIOS version will provide
When you say the previous mobo 'has burnt out again', what do you mean exactly, what were the possible causes & how many have met this fate?
The usual procedure is to fit all the basic parts together: CPU with cooler, RAM, graphics card (with power if required), PSU, plus at least one hard disk & optical drive. Then in the BIOS set PC to bootup from the optical drive first & install your OS. G