Yes it is very dangerous(if it fails, you are screwed without another bios chip, if it works, great!), but if you are going to take it back(if it doesn't end up working)then you'll be ok. It should be ok, just make sure you don't reboot or anything while it's writing to the bios chip, and save the curernt bios to disk. There are ways to get around it if it goes bad, search around for bios flash or something in the forums, or
http://www.badflash.com I think.
edit: Yeah it happened to me, fixed my problem until my board died! But i'm much happer with my Iwill now. It is odd that it will only let you do 100-132. Make sure you have the jumper set to 133FSB instead of 100. It should say where it is in the manual..you might want to try this before you update bios.