Well i used to work at sound hound which solded plasma tv's and LCD's, they are not really that hard to put up yourself, if you have a drill and most importantly a spirit level, do u already have a bracket for it?,
If you need a hand i would be happy to help but if you are thinking of running the power cable and the sky/ tv cables in the walls you really must get a company that specialise in installations beacause from past experience they is a good chance it wont be as easy as it looks, alternatively you could always run an inch thick piece of conduit to hide the cables and this can be painted over, it will also be a lot cheaper.
I need the second option I'm afraid as I would like it installed properly with cables in the wall. I'm a bit of a botcher with DIY and don't fancy a) damaging the TV when it falls off the wall, b) damaging the wall!! Thanks for your reply and your offer of help though.