You are wrong. MS posts on their product lifecycle page that support for Vista is planned through 2012. And that an extended support plan will be good until 2017. So I wouldn't worry about support.
As for testing and proving, I think most people prefer not to gamble with their money. It's a smart move to go with what the vendor (TGC) says is required, and go with what they support. You're completely free to buy X10, get the source from the Alky Project, or Wine, or whatever the flavor of the month is, and have a go at it!
Cheers!
"Everyone has a plan 'till they get punched in the mouth" -- Mike Tyson