> Do we have to uninstall the old version before we 
> install the newer version? Or can we just install it 
> over the old version.

The best is to uninstall the previous version, because 
the install system has changed (from installshield to 
InnoSetup), the new install system (single .exe) 
should be less bogus and more reliable, especially on 
NT systems without admininstrator rights.

> If so then will we loose our cache and downloaded 
site files?
The "My Web Sites" is untouched, whatever the version 
is, even if uninstalling/reinstalling.