Yes, it is true. Windows Vista to Windows 7 upgrade can take 1,220 minutes on some PCs with 650GB of data, 40 applications, on mid-end hardware, and during a 32-bit upgrade. The other interesting point worth noting is that the 32-bit upgrade is faster on a clean install than a 64-bit upgrade, regardless of the hardware configuration, and is faster on low-end hardware, regardless of the Data Profile.
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:bulletblue: Windows Vista to Windows 7 upgrade can take 21 hours on some PCs