Marco, it's worth checking with your parents what particular channels they like as, whilst both Freeview and Freesat have the same core channels, they differ in their provision of the smaller ones. As an example off the top of my head, Freeview has Dave and Quest but Freesat doesn't, whereas Freesat has the likes of CBS Action and the Horror channel but Freeview doesn't.
Channel lists here for Freeview: http://www.freeview.co.uk/whats-on/channels
And here for Freesat: http://www.freesat.co.uk/channels
We had an enfoced change to Freesat when we moved house two years ago as there is the square root of naff all Freeview signal where we now live - luckily there was already a dish on the house. I bought a Humax Foxsat HDR box and have to say I've been very impressed with it and don't miss Freeview at all. Well, apart from when I have the occasional hankering to watch a repeat of a 2003 episode of Top Gear on Dave, but that doesn't happen all that often... As a bonus, the Freesat signal is stronger and generally much more reliable.
The Currys all-in price does sound quite good but, then again, this does mean dealing with Currys - caveat emptor!
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