Okay, you probably don't want to host one of these parties. But I do.
You make it seem like hosting a party is a big, bad thing. Like dropping $250 on food is a big deal. That Microsoft is EVIL for thinking you might be a normal person who has friends, and who regularly invites those friends over to your house so you can get together and have some fun. With friends.
The ONLY thing Microsoft is asking you to do, is to have a machine running Windows 7 at your house. They will give you a copy of Windows 7. They will also give you some other things (napkins, balloons, etc.) that you can use if you want.
You can also win a new computer for yourself.
I don't consider that to be such a bad thing. I regularly have parties anyway. The only difference here is that Microsoft is giving me a copy of an operating system (which I can choose whether or not I want to use) and a few other things.
And if you have friends...real friends...it is easy to say, "Hey, come on over to my party...yes, it will have some strange decorations, but that is no big deal."
For my friends, it won't be much different than my burger building parties. Or my 'Throwdown' (cooking contest, not WWF) parties. Or my Rock Band parties. Or anything else.
It's just a fairly flimsy excuse to get together with friends.
If that seems evil to you, then I think we have vastly different opinions on life.