Chris's list of AMI beep codes points to three beeps being a memory error, but with the fan on the video card not spinning, you might have two issues, or the video might be the root cause.
Your GeForce4 MX 440 is an NVidia AGP 8x card. If you want to stick with one of those you'd probably have to find it 2nd hand. There are other cards that will fit the bill, they just make it a bit more complex because you have to change video drivers.