extract time as hour with am/pm from datetime

Hi I have a date time field in sql server 2005 that I want to extract the hour with am or pm after it. I created a monstrosity to do this, it works but there must be a better way?

      cast(
            case
              when
                  cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer) > 12 then
                    cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer)-12
              when
                   substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2)='00' then 12
              else
                    cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer)
              end
              as varchar(10))+
            case
              when
                  cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer) > 12 then
                     'pm'
              else
                     'am'
              end  
       as v_timeStart Free Trial

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cast(
		case 
		  when
			cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer) > 12 then
			  cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer)-12
		  when 
			 substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2)='00' then 12
		  else
			  cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer)
		  end 
		  as varchar(10))+
		case 
		  when
			cast(substring(convert(varchar(10), ttimeoffirstmetering, 108),1,2) as integer) > 12 then
			   'pm'
		  else
			   'am'
		  end  
	 as v_time