Don't know if the 3000 had the "post lights" on the back of the unit or not, but you might check to see.
Good chance the Power Supply has crapped out also. Even though it is trying to boot, there is not enough power to the devices to boot. I believe it is a low end 250 Watt unit, that goes for around $30-$40 (including shipping). I ordered one from this supplier for a Dimension 4400 which worked fine, should you be interested:
http://www.discountelectronics.com/index.php?l=product_list&c=1&c=306&c=147&c=5236
If you decide to replace it, make sure the connection to the MOBO has the same # of pins (20, I think). And, of course, being a DELL, you can't use a standard digital PSU tester because they switched some connectors to make them proprietary ! But you could always use the Multimeter !
Hard to put old friends to sleep !