That sounds feasable to me m8,

Feed comes in and splits to TV/MODEM
Split feed to TV gets Boosted then split into 4 feeds to other STB's.


Just make sure you check your signal strength and BER using your current 500c before you go buying different boxes.

It will work as I had 5 modems and a STB all running from the same feed...when I was experimenting with downloading at high speeds to the same PC & was getting crazy speeds.