OEM Vista 64 on parallels ?

Hello everybody, you will right away see that I am a bloody greenhorn. So in advance please foregive my stupid questions.
Reading now for 2 hours about OEM versions I think OEM should work with Parallels and is legal. But 2 things remain unclear: 1. while downloading OEMs OS I have no cd/dvd. what to do? just burn a cd? 2. It is said somewhere in the threads that Vista 32 will work but not Vista 64 on bootcamp? (what ever that means .....) But I will use Inventor 64 bit and therefore need vista 64 bit version.... , any comments are highly appreciated. Eckart