Trouble getting into the BIOS

So I just built a new pc and got it up and running with relative ease but I've run into an odd problem. I entered the bios just fine before installing my os and set my dvd drive to have priority on booting because I had installed a release candidate of windows 7 because I couldn't find my copy of windows 7 ultimate anywhere and wanted to just reformat and start from scratch. Now after I installed windows 7 ultimate and the driver dvd for my ASUS P7P55D motherboard and try as I might I can't get into the bios no matter how hard I smash my delete key which worked before I installed said drivers.