So by now I guess everyone knows about this trick:
http://www.dailytech.com/article.aspx?newsid=5932

The question is, how can Microsoft fix this? My actual question is "should I go out and buy an upgrade DVD before they make a new batch that doesn't allow this", or should I not bother because Microsoft can just tweak their activation scheme to prevent anyone from doing this, even using an old DVD.

It seems to me like there's nothing they could possibly do to prevent you from installing Vista in trial mode with one of the current upgrade DVDs. This can all be done with the internet unplugged up to the moment when you're done installing the second time and you just need to activate your working install of Vista, correct?

So what could they possibly do? Can they check that you didn't really come from a previous XP/2K install and deny your activation based on that? In which case I guess even with a "first batch" DVD you would still not be able to use this workaround?