So, after the brouhaha regarding the public beta release of SharePoint 2010 it seems that installing the product is not straight forward when using Windows 7/Windows Server 2008 R2.
There's an issue with WCF in .NET 3.5.1. where SharePoint relies on an attribute that isn't present, namely AllowInsecureTransport. You can simply remove this from the client.config files but this will break other services. There is talk of other work arounds but at the minute, the official advice if you want to run SharePoint 2010 Public Beta on Windows Server 2008 R2 is to wait for the official WCF Fix from Microsoft.
When this is available, it can be downloaded from: KB976462 at present this is not available.
Note: There is a WCF Fix available for Windows Vista/Windows 2008 which will fix this issue which is available from here KB971831 note that this fix is NOT for Windows 7/Windows Server 2008 and if you attempt to install it you will receive the "This update is not applicable to your computer" error and the install will terminate.