Definitely not a job for the weekend warrior.
First trick is to make sure you get the wall bracket into the centre of the studs. Second issue is keeping the cabling away from the heat shield. Third trick is not to drop it. That's just the basics.
Highly recommend going to your local FutureShop and getting a free in-home consultation. I think a basic wall mounting is somewhere around $200-$300 bucks but is professionally installed, TV is calibrated to THX standards, the techs will also give you a tutorial on your system so you know how to use it to it's full potential, and their work is fully guaranteed for a year. Well worth the investment.
