Well done Mighty Higs for posting that chart – most folk don't realise the distances required to benefit from HD.
I install TV/Home Cinema professionally so my advice would be:
In that size room get a 50" screen – no question. It won't seem big after a few days. If you get a 42" you'll soon realise you could've gone bigger.
Get a Plasma – I'd recommend LG if you're on a budget. The LG50PS6000 should be around £800 and looks cool as well as performing well. Good deals on Samsungs can be had too.
Buy from John Lewis (who will price match) or Costco. Both give a FREE 5yr warranty. If buying on the web look for 5yr warranties or at least buy from Pixmania (French site so 2yr warranty). Richer Sounds can be good if you have a local one. Their 5yr cover is cheap(ish). DON'T buy from Comet or Currys and get swindled by their extended warranties.
Extending/tilting brackets can be sourced on the web/eBay for £50 or less. Don't buy one in the high st for £150. A 50" Plasma is around 40kg but a properly fitted bracket will hold it fine – even with a swivel arm. Little bit of DIY knowledge and it's easy to fit – just take your time.
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