You can sign up and attend an Microsoft event. They always are giving away copies of Vista, Office 2007, and Server.
I scored a free copy of Office 2007 by watching 4 dumb online presentations. Just scour the hot deals Web sites for deals like this.
You can also install a copy of Vista without a key and run it is a trial for a few weeks. However, after a few weeks, you'll need to buy a new key if you want to continue to use it.
Hmm, well since I live in a hick town in Canada it sounds like I'm going to have to pay. How am I to install vista without paying for it? You mean borrowing from a friend?