MacBook Pro heating problem?

I have a 2011 MacBook Pro 15''; i7 and 4gb. I'm really worried about the heating.I usually play The sims 3 and as soon as i start it the temperature goes REALY high.I do not have it on my lap,i always have it on a table. This is my first mac.I've been using 'Temperature Monitor' to monitor the temperature and when i play a game,the temp of the CPU were about 80C-90C(sometimes 94C).Now i have installed iStat but the temperatures seem really low but if u touch the space between the keyboard and screen,you'll get burnt. Can anyone tell me what app is good to use to monitor the temperature and what are the usual temperatures of a mac. THANK YOU!