Yes, you'll either have to get a Sky HD box which is �10 extra a month or buy a Freesat HD box which is a one-off payment, but obviously without the Sky channels
No, not Freeview - it's FreeSat - they are TOTALLY different things, Freeview comes via your aerial and has no HD channels, FreeSat uses your existing (Sky) satellite dish and has quite a few free HD channels, BBC, ITV, Lux TV etc.
To confuse things even more, there is also a service called FreeSatFromSky - from Sky, which is just like Freeview (i.e buy a box, no contract) but on satellite and has NO HD channels. Confused yet??