[At_Libitum]

And a word of warning.

If you DO go with the PortableApps version, AND you place your Libraries inside the 'portable' folder structure. Be sure to move them out of that folder structure if you ever decide to uninstall Calibre via the PortableApps method as it WILL kill your libraries. I would advise to not put them there but in the portable documents folder.

But, if you do decide to go PortableApps, it has a relatively unknown feature. When an update is released to Calibre Portable, just download the official Calibre portable release, place the file in the same folder as the portable apps launcher and it will automagically update Calibre in portable apps structure. Just be sure to remove the update after it's done or it will do the same on the next launch (even though it's already updated, the mere presence of the file triggers the process)