you need at LEAST a 30" dish and a KU Band LNBF to get 105 or 121.
Or get the Superdish..they are running a deal that if you agree for a year to the int'l channels you want, they'll bring out the dish, install it, and give you all hardwrae to receive it at no charge.
Fully agree with Iceberg...105 and 121 need at least a 30" dish and both are FSS birds. If you thinking of doing this to save some $$ look for a discarded Primestar dish.