Can't boot into BIOS

Hello,
I recently reinstalled windows 7. After installing most of the programs I normally use, I wanted to boot into BIOS to check the harddrive priorities. But somehow I can't anymore. I'm using a Gigabyte motherboard. Whenever I boot up the computer, it would show a screen with a guide underneath, "DEL - Bios" etc etc.
I tapped the "DEL" button nonstop but it doesn't boot me into bios. It did before, but not now. It just boots me straight to Windows.

What is the problem? How do I fix it?