I am not sure if you can do it now because normal enrrollment is from 11/15 to 12/30 end of the year,unless you just entered in 2010 then you can choose from many companies like aarp which is managed by united health care whom i consider from many others as being best formulary .All companies associated with medicare have about the same cost but the great formulary of uhc is by far the best.The cost is a supplement to your regular part d that covers meds but due to the supplement your copays are almost nil up to 2600.00 expense so far until the so called dpughnut is aproved by congress.
In addittion i would also recomend to have also through aarp uhc the supplement of yor 20% coverage.It dependes a lot on your utilization of services meaning how really unhealthy you are,as in one single visit to a doctor that orders plenty of radiological studies your 20% will be greater than the anual cost of the supplement that runs about $3000.00 for the year,except if you have medicaid or are eligible for it do not change anything as medicare and medicaid is really your total platinum gold card fro health coverage anywhere,anytime etc.
