Recently, my Dell Dimsension XPS PIII tower has begun "noising up" and I'd like a general idea of what may be occurring! Having never opened up a case before, I'll give the outside symptom: whatever main physical drive (running all the time) located in the middle of the tower in the lower quadrant is producing an off-kilter "whirr-whirr, whirr-whirr, whirr-whirr..." Shutdown and cold boot often starts off smoothly. I defrag regularly FWIW. I worry it may seize or grind to a halt the longer I hold off having it looked at. I am still under 3-year service. Any thoughts, pls?