Dell Inspiron F Keys

Hi, I have a Dell Inspiron 1545. My F1, F2, F3, etc. keys by default have other functions when pressed (like turning wireless on/off, changing the volume, playing and pausing media). I have to hold the 'Fn' button while I press these keys to actually get them to function as F1, F2, etc. I'm wondering if there is a way I can lock the F keys so that they will act as F1, F2, etc. without me having to hold down the 'Fn' button? Thanks.