Can't stress this enough.

After upgrades, moving computers and installing and configuring everything multiple times, I went the portable route.

Now, for every application I install the portable version is my first preferences. Every few months, I backup application paths and configuration files which are outside of the portable installation paths. Some applications keep local MRU files or some other settings in the dot folders under the user directory.

Of course, the portable applications directory also gets backed up on a regular basis.

Nowadays, a recovery from an operating system failure, results in a downtime of less than an hour.