You can LEGALLY download 60 day trial media here:http://office.microsoft.com/en-us/try/
That can also be turned into a retail copy, when you go buy your retail key and put it in when it asks you. I've done this for several computers before running to the store to buy a key (the key itself is cheaper than boxed media, anyway). It cannot, however, last more than 60 days without said retail key. Go buy one. Best Buy and Sams Club sell them, among other places.