Earlier, I did a couple of fresh installations of Windows 7 and found it agreeable, so now I’m upgrading the Vista VM running on my iMac with Parallels 4.0. This has presented various points of interest .

1. You can do an in-place upgrade from Vista to Windows 7, but not from Windows XP.

2. I had to increase the size of the Parallels Vista VM disk from 30 gigs to 48 gigs to accommodate the installation files for Windows 7. You do this in Parallels through the Parallels Image Tool which expands the disk partition size. Before doing this is will merge any snapshots that you’ve taken. I had only a single snapshot that I had created when first installing Parallels a year ago. Rather than allow this merge, which would have taken several hours, I exited out of the program, deleted the snapshot through the snapshot manager, then reentered the Image Tool and performed the expansion in a about 30 seconds.

3. I increased the available RAM from 1 gig to 2 gigs, at least for the installation, since it was a stated requirement to have more than 1 gig. I may crank it back to 1 afterwards.

4. Among the steps during an upgrade, there is “Gathering files, settings and programs” The count of these was 414,061. That is not a misprint. Amazing, after less than a year of running this particular Vista workstation how much crap you accumulate. I’m also wondering at how they calculate the percentage in the upgrade status screen (above) which doesn’t seem to correspond with the numbers.

My guess is one reason XP isn’t supported for an upgrade is that XP still runs nicely on smaller, older machines, and these are probably not good candidates for a Windows 7 upgrade… notwithstanding the fact that Win7 is supposed to have a smaller footprint both in disk space and memory requirements than Vista. Accordingly, any machine that can run Vista should be able to accommodate Windows 7.