This seems to be an easier way to change it: http://www.techpowerup.com/forums/showp ... ostcount=8
Apparently, this can give you a great boost in WinRAR benchmark (google cache as the direct link doesn't seem to work anymore): http://webcache.googleusercontent.com/s ... clnk&gl=us
Not sure if I'll try this or not. Disabling core parking could theoretically decrease performance by having the threads bounce around cores, though maybe since the core i7s have inclusive L3 cache the hit is negligible? It would be cool to see a TR review on this *wink* *wink*.
For what it's worth, I'm also seeing some people say that SP1 of W7 fixes the core parking performance hit.