Loud fan sound

You have a "No POST" situation. Check the power button, more than likely it is not a solid green.

Your computer is probably old enough to have lifetime troubleshooting support from Dell, if you are the registered owner. They won't replace any parts (but they should help you figure out exactly what _is_ wrong).

I will say that unless you are prepared to do the work yourself, repairing the system will cost nearly as much as buying a new (and much faster) computer. With the economy the way it is, there are some great deals to be had. You'll only need a box, so check out outlets like dellauctions.com.