Saw your comment about the set costing £2500. Seems overpriced but there again, that was a big set 17 years ago.
Yes, you can use an external set top box (Either Freeview or Freesat) to get digital TV and you can opt to have one with a built in hard disk recorder, into the bargain (PVR). Check out Humax.
There's no need to get a high definition PVR as your set wouldn't do justice to the picture and you'd need to make sure that whatever set top box you do get has a SCART output as your set doesn't have an HDMI connector.
In all honesty, I'd be tempted to spend the money that you'd shell out on a PVR on a branded high definition 40 - 50 inch LED set (but do check out the sound quality)