I have a 50in Samsung plasma on my int wall that has held fine for the past 2 1/2 years. There is a few things you must remember.
#1 What size are your wall studs? (I have a mix of 2x3 and 1x3 in my walls every other one)
#2 It is advised that you sister up some studs to the others if you have the small studs.
#3 MAKE SURE YOU DRILL THE CENTER OF THE STUDS WHEN YOU HANG YOUR WALL MOUNT!!!
#4 Make sure after you drill a pilot hole you use the correct lag bolts or you will split your studs.
#5 When you have your wall mount in place before you hang the TV hang on it yourself. (I am 230lb man and it held me for a wile) You want your mount to hold at least 2 times the weight of your TV. (My 50in plasma is 105lb)
#6 DO YOUR HOMEWORK (Where do you want the TV, what mount to buy, the correct mounting and hardware for your mount and TV)
#7 If you do run cables in your wall (I did) make sure you hook up one or 2 extra cables for future use and MAKE SURE THE CABLES YOU USE IS RATED FOR IN WALL USE!!!!! I CANT stress that one enough. If you had a fire or other problem and you did not have the correct rated cables your insurance may give you the bird!!!!!!!!
#8 Have fun with it and do it right. It looks so good when the cables are hidden and the TV is up on the wall.
There are a few good places on the web to buy the wall mounts and cables you need for great prices. I like www.monoprice.com
for wall mounts and any cable you need.
NO I am not a salesman for them or anything like that I just hate seeing people blow huge $$$ on overpriced monster cable and other overpriced name brand junk. Over $100.00 for a Monster Cable brand HDMI when I can get the same cable and same quality for $5-10.