{ ... }

var

  strOLE: string;

begin

  strOLE = "YourCOMServer.Application" {your ProgID}

  if (CLSIDFromProgID(PWideChar(WideString(strOLE), ClassID) = S_OK) then

    begin

      { ... }

    end;

end;

{ ... }

const

  cKEY = '\SOFTWARE\Classes\CLSID\%s\InprocServer32'

  var

  sKey: string;

  sComServer: string;

  exists: boolean;

  Reg: TRegistry;

begin

  Reg := TRegistry.Create;

  try

    Reg.RootKey := HKEY_LOCAL_MACHINE;

    sKey := format(cKEY, [GuidToString(ClassID)]);

    if Reg.OpenKey(sKey, False) then

    begin

      sComServer := Reg.ReadString('');

      if FileExists(sComServer) then

      begin

        { ... }

      end;

    end;

  finally

    Reg.free;

  end;

end;