I pre-ordered Vista Home Premium 64-bit edition from OCuk (stunning prices and all) and I am wondering if I can simply update my current OS which is Windows XP Media Center to Vista and retain all my files and programs, or does it have to be a clean reformat and install? Normally I wouldn't ask this question as previous Windows OS's have updated over one another before, but it is a leap from 32 bit OS and applications to a 64 bit OS this time around. This is why I am unsure