Can't get Wifi on Vista..?

Alright, so I have a Dell Inspiron 1545. It came with Window's 7 on it. But I got a horrible virus, blah blah. Anyways, one thing lead to another and I had to wipe everything and start from scratch. But we didn't have a Window's 7 disk for some reason. So I had to install Vista, which we did have a disk for. Anyways, I can't seem to turn on the wifi with the wifi hotkey like I could when I had Vista. So would someone be able to walk me through what I need to do to catch the wifi signal in my house?