If you want to go 'freesat' I'd forget the integrated TV sets and wait for the HD PVR - which is a must have piece of equipment.
However I've already gone the Sky route and have the Sky HD PVR. HD is OK but doesn't improve poor content and often good content doesn't need HD. In my opinion it's hard to justify spending big money just for HD. However if your upgrade delivers HD, as well as everything else at little or no extra cost, then it's a good idea.
Or you could wait for the limited HD offerings via Freeview - when it arrives.
The most interesting channel(s) on HD are the mixed definition channels like C4 and Sky One. Here you see the medium term future for most of us - some HD mixed in with lots of Standard Definition SD TV. It's interesting to note how good some SD TV can look on a decent HDTV and also how poor some expensive BBC HD looks on the same TV - Criminal Justice was a prime example where expensive HD was reduced to SD standards by poor production.
HD does generally deliver a better picture but I'm not sure it makes a programme more watchable soley because of that. It's the content quality that's most important.