Is additional cooling neccessary?

Im building a new comp soon and i dont know a whole lot about computers but i do know that they get hot so im wondering if stock colling is best for this setup

i7 920
asus x58 mobo
gtx 275
6 gigs ram. Does it effect heat of computer?

im getting the antec 1200 chassis and ive read it good at cooling but i dont know if its enough
oh and i probly wont overclock, if i do it wont be by me lol but if i do what could i overclock it to before i need new cooling stuff if i already dont?

Thanks!

cool thanks