Two important things to remember: first, it's the tip of the probe that senses the temperature, so make sure that the tip doesn't go through your meat and touch a hot rack or cooking grate. Second, do NOT let the probe/cable connection touch water!!! It can be submersed in cooking oil, but not water.
Actually Lee, depending on the thermometer you get some of them register the heat higher up then others. That is one reason I like my Thermapen. It is very close to the tip. Some others are a bit further up the shaft.
I was at a kitchen supply outlet today and they recommended that I go to our local Loblaws grocery (Canada only I think) and get one of their thermometers, under the Presidents Choice brand. I did and I used it to cook a nice prime rib roast. I was out, so my wife only had to take it out when it beeped at 145 f . The roast was perfect and the cordless thermometer only cost me $25.