A quick one for this evening before I fly out to Hong Kong tomorrow morning.
For many years, there have been the concept of “upgrade versions” of software (i.e. a mechanism to move up a version usually with the prerequisite of a prior, eligible version) and “full versions” of software (which has no such prerequisite). Windows is a prime example of this approach (putting aside the fact that with Windows Vista you can install the upgrade version as a clean install (which will work for thirty days) and then upgrade over itself again. A full guide on how to do this can be found at Paul Thurrott’s SuperSite for Windows.
At any rate, software upgrades can leave a lot of cruft over time, especially major ones such as operating system upgrades which can preserve the former operating system in a folder just in case you want to go back. Temporary files, registry keys and DLL files can be scattered all over the place without being cleaned up. Even uninstalling software can leave rubbish behind.
So what do you do?
Depending on how frequently you install and remove software, I would recommend a clean installation perhaps once every 12 to 18 months. For many, this can be a time consuming process which is why making a backup of a pristine system that can be recovered quickly is a bonus. An added benefit of a clean installation is that you also deal with the problem of disk fragmentation that gradually increases over time.
I have come across computers that have not had a clean reinstallation for as many as eight years with the original factory installation intact and the Start Menu absolutely choked with three columns of software. It’s scenarios like this that have people upgrading their computers regularly because it increases the perception of an inadequate computer when, in fact, the accumulated rubbish is the cause of the slowdowns.
So whilst you may have to invest about half a day to a fresh install on an existing computer, it will keep your productivity up and your computer responsive.