!!! Geek warning !!!

I'm confused. I just bought a new computer, and of course I had to mess around a little, and now I'm having slight boot problems. My computer doesn't boot by itself. I need to tell it where to boot from, otherwise it can't find anything. The problem is not the boot sequence, the setup tells me the HDD is not available. I have spoken to a few friends about it and they do not agree on what to do. One told me to reset the BIOS, whereas another advised me not to do it.

Currently the score stands at 1 with restarting the BIOS - 2 against.

Let the voting begin !! =PP