Why can't i see a difference between geforce 8600gt and 8800gt??

can some please help me understand why my games still look the same with my new geforce 8800gt?am i playing the wrong games?(orange box,NHL 08,Madden 08)or is it my monitor? i have a bulky regular monitor with the blue pinholes..i just spent $150 on it and it was like pulling teeth out of a lion to install it..did i waste my money?i had a 8600gt 256mb ddr3..my 8800 is 512mb ddr3,but i don't see a difference.oh,and i heard this card gets hot quick,how do i cool it down?sorry,i'm new to all of this..it's my first computer..thanks guys i really appreciate your time..