Here we go again. Senior citizens now have six weeks to sign up for another year of Medicare Part D -- the prescription drug benefit -- that goes along with Medicare Part A (hospitalization), Part B (outpatient and doctor costs) and Medigap (the supplement that covers other costs including co-payments and deductibles).It's a must-do project, even if you're among the few seniors who don't currently take prescription drugs. If you don't sign up when you first become eligible, there will be big penalties to pay once you do need some prescriptions -- and for sure you will need them at some point. The only exceptions are those seniors who are covered by a comparable company or retiree prescription plan, or those who have signed up for an all-in-one Medicare Advantage plan. Some seniors have prescription drug access through the Veterans Administration, though they may want to choose an inexpensive Part D plan for drugs the VA does not cover. For those who recently turned 65 and now qualify for Medicare, this will be the first time going through the process of choosing the least expensive plan. But every senior, even those currently enrolled and happy with their drug plan, should go through the process of reviewing the alternatives for 2009. That's because each year the plans change the prices of the drugs they cover, and may not even include the same medicines in the year ahead. So, here's my annual, step-by-step guide through the Medicare.gov Web site, the only place that can sort through all the alternatives plans to find you the best coverage at the least cost in a plan that is available at a pharmacy near you!