With Windows Vista, Microsoft is about to release the most widely distributed piece of shareware ever.
Oh, I know they’re not calling it shareware. In fact, Section 8 of the Vista license agreement specifically says you may not “lend the software.” But there’s nothing that technically prevents making copies of the Vista DVD, and you can install that copy on any computer without a product ID, with no activation required for 30 days. At the end of the 30 days, your copy of Windows Vista will shift into “reduced functionality mode,” at which point you can wipe it out and start over, or pay Microsoft or one if its partners for a license.
That sure sounds like “try before you buy,” doesn’t it?
I certainly don’t recommend this strategy to anyone. But I won’t be surprised if a lot of people, especially enthusiasts, “borrow” a copy of Vista and try it out for 30 days. Microsoft might be betting that when the month is up, enough people will be pleased enough that they’ll pay up.
Ed Bott (@ wordpress.com) 
Even if they can install it without a product ID, wouldn’t they still need to call Microsoft to get one of their own?
Kat, as I note in the post, you can install without a key and run for 30 days without having to talk to Microsoft. At the end of 30 days, you can buy a key online, buy one at retail, or reformat and start over.