PC question, anyone experts?

My eMachines T1840 is running two internal hard drives, one ATI radeon 9200 graphics card, one 24 bit Sound Blaster sound card, one unused wireless PCI card, two DDR 400 1GB memory sticks and a pentium 4 cpu running at 1.9935 Ghz. I have changed my existing PSU from 250 watts to 400 watts. My problem is this: For about two weeks after I switched to the 400 watts PSU, I have been hearing occasional clicking noises coming out of my hard drive D. But now for quite a while I do not hear the clicking noise anymore and my D drive is functioning properly as always. Does that mean that my D drive will not function properly in the future?