Agreed with Jaquith, one beep is what is supposed to happen. It generally means that the processor got responses from all the hardware.
Are you sure that the video cable is plugged in right?
There is a built in graphics port on the motherboard, if you have the video card installed it will be disabled by the computer so if you have the video plugged into the motherboard port while the video card is installed you will get nothing. You would have to change the cable to plug into one of the ports on the video card.
If its already in one of the ports on the video card, then you can try taking out the video card and plugging the cable into the motherboard port and see what happens.
Also, your monitor may not auto-detect which input stream to use between digital and analog. if it is set to receive analog and you have digital plugged in then it will show nothing (and vice versa). You can play with these settings by using the buttons on the monitor which are usually located in the lower right.