hey I've bought my 13" MBP (love it) but need to dual boot to run some programs, so I bought the Windows 7 Prof 64bit Upgrade. Now... because it's the upgrade version do I need to have a previous version of a Windows OS installed before I can upgrade or can I install straight away? Another question, at some point I'm tempted to upgrade to the 500gb Momentus XT. Will my Windows 7 disk be okay for multiple installs? Thanks very much.