It's nothing like drivers, because unlike a failed driver a failed chip just sucks. No really though, you need an external programmer and another computer to re-flash a failed bios attempt. It's not as dangerous as I'd say the people above posted, but it is something that you should double check everything. Like if I'm going to make a floppy disk for flashing, I don't just make the disk I check it a couple times to make sure it boots ok. Because if you get any corruption and the CRC checks out your screwed. It's really like updating DVD/CD firmware, just make sure you do it right cause a bad flash means dead parts. Usually most MB's now have a flash program built in, like when you boot and you see "Hit F5 for AWD Flash Utility". In those cases all you need is a CD or Floppy with just the .bin file of your bios and the rest is "Press Enter". Gigabyte boards have made dual bios boards, just for things like this (I love that option, I think everything should have some form of perm flash backup).
I do agree though that you don't need to update the bios unless you have a problem. My ASRock has a win flash program, I didn't even know it was all automated until I ran it thinking "Oh it'll give me an option to continue". No, it just checked the flash and started flashing which scared the **** out of me. Why? Cause I didn't know for sure if the computer was stable, which it wasn't cause I had unlocked 2 cores and one had a bad L2 cache... I'm lucky this all went well! But you can flash from within windows, it's no different from flashing outside of windows, really the flash still has to be sent to RAM and 8bit sections erased and flashed.