My 5 yr. old throws temper tantrums...?

My son is 5, very smart, but likes to throw fits when he doesnt get his way. I dnt have alot of patience so my first reaction is take away whatever the fit is over, send him to his room & let him "get over it". Once he stops kicking the walls or screaming at the top of his lungs & cools off.. i DO go in the room & talk to him abt the situation. While im trying to talk to him he always stares off or something else easily catches his attention.. so im not sure if he is really realizing why he got into trouble? But my question is this. How can I prevent him from kicking & screaming before it goes that far. I have tried . doesnt work.. fit's only escalade. my temper is blown. then i finally just say forget it & walk away. He still ends up w/ what he wants. I've tried time out in the corner. doesnt work. He falls out in the floor, kicking & screaming. So this is why i have resorted to the room & the "get over it" process. Im so scared he is going to start school & have no friends bc he doenst want to share or hits them or whatever the case may be. He is too smart to be acting like this! I still love the little rascal.. i just wish he had a behavior "ON" & "OFF" switch =) Thanks in advance to the replies.. all help will be appreciated! <3