Hi all,
I've updated this page with more up to date information on setting up a good IIS 7 platform for SilverStripe:
http://doc.silverstripe.org/doku.php?id=installation-on-windows-manual-iis
SilverStripe is very running happily on my Windows 7 Ultimate x64 box with PHP 5.3.1, IIS 7.5 and SQL Server 2008 w/ SP1.
Sean